physics

  1. A boy is swinging a toy on a piece of string in a vertical circle. The toy has a mass of 150g & the radius of the circle is 0.8m. A. he swings the toy with a linear velocity of 2m/s will the toy move in a circle? Explain your answer.

  2. Many competitive swimmers practice in loose-fitting, baggy swimsuits called drag suits. In 1–2 sentences, explain how, in terms of the forces acting on a swimmer, wearing a drag suit differs from wearing a tight-fitting racing suit, and why practicing in

  3. A ball of mass 0.2 kg strikes a force sensor and sticks to it. Just before impact the ball is travelling horizontally at a speed of 4.0 m s–1. The graph shows the variation with time t of the force F recorded by the sensor.

    (plus there is this graph where

  4. 70-kg man jumps off a raft 2 meter squared moored in a freshwater lake. By how much does the raft rise?

  5. a girl is using a rope to pull a box that weighs 300N across a level surface with constant velocity. the rope makes an angle of 30 degree above the horizontal and the tension in the rope is 100N. What is the normal force of the floor on the box?

  6. A boxcar of mass 250 tons at rest becomes uncoupled on a 4.0° grade. If the track is considered to be frictionless, what speed does the boxcar have after 11 seconds?

  7. if two forces 10N and 20N are inclined at angle 60degree to each other. Find the resultant force.

  8. a roller whose diameter is 20 in weight 72 lbs. what horizontal force is necessary to pull the roller over a brick 2 in high when (a) the force is applied to the center, (b) at the top

  9. A physics book of unknown mass is dropped 5.00 m. What speed does the book have just before it hits the ground? Assume that air resistance is negligible

  10. A load of 80N extends a spring by 8cm. When the load is replaced by a copper block, the extension produced is 10cm. Calculate the weight of the copper block, assuming that the elastic limit of the spring is not exceeded.

  11. Why is Newton’s cradle (Newton’s balls) described as an “almost-ideal” closed system?

  12. If a line of dominos is knocked down, which statement can be concluded about the dominos?

    An increase in acceleration caused an increase in force. An increase in force caused a decrease in acceleration. An increase in acceleration caused a decrease in

  13. A large metal ball is at rest, and a small rubber ball is moving at a high velocity. When they collide, the large metal ball begins to roll slowly. What must have happened to the momentum of the small rubber ball?

    It must have stayed the same. It must have

  14. A 4.0 kg, 36-cm-diameter metal disk, initially at rest, can rotate on an axle along its axis. A steady 5.5 N tangential force is applied to the edge of the disk.

    What is the disk's angular velocity, in rpm, 4.0 s later?

  15. Which series of steps describes how to demonstrate conservation of momentum in a system of two moving particles that collide?(1 point)

    Determine the momentums of one of the particles before and after the collision and add them together. Determine the

  16. What is the tension in the rope of this figure description?

    60 kg person is hanging in the air on a rope attached to a pulley, with a 100 kg mass attached on other end that is touching the ground.

  17. a concrete slab of mass 400 kg accelerates down a concrete slope inclined at 35 degrees. the coefficient of kinetic friction between the slab and slope is 0.60. determine the acceleration of the block

  18. A block with mass m =7.3 kg is hung from a vertical spring. When the mass hangs in equilibrium, the spring stretches x = 0.21 m. While at this equilibrium position, the mass is then given an initial push downward at v = 4.5 m/s. The block oscillates on the

  19. Using two billiard balls, in 3-4 sentences, design an experiment to demonstrate the law of conservation of momentum.

  20. Tension is maintained in a string. The observed wave speed is 21 m/s when the suspended mass is 3.0 kg.

    a) What is the mass per unit length of the string? (in kg/m) b) What is the wave speed when the suspended mass is 1.6 kg? (in m/s)

  21. The position of a toy locomotive moving on a

    straight track along the x-axis is given by the equation x = t4 − 6 t2 + 9 t , where x is in meters and t is in seconds. The net force on the locomotive is equal to zero when t is equal to

  22. Wavelength In Different Media Quick Check

    1.) The sound of a plucked guitar string travels through the air and strikes the eardrum of a person in the same room. How does the sound wave change when it transfers from the air to the person’s eardrum? -Both

  23. When an earthquake occurs, two types of sound waves are generated and travel through the earth. The primary, or P, wave has a speed of about 8.0 km/s and the secondary, or S, wave has a speed of about 4.5 km/s. A seismograph, located some distance away,

  24. A geologist finds that a Moon rock whose mass is 9.97 kg has an apparent mass of 6.40 kg when submerged in water. What is the density of the rock?

  25. when a 2.50 kg object is hung vertically on a certain light spring described by hookes law the spring stretches 2.76 cm. A) what is the force constant of the spring. B) if the 2.50 kg object is removed how far will the spring strecth if a 1.25 kg block is

  26. The same type of engine is placed in two different airplanes. The first airplane is twice as heavy as the second airplane. Which statement is correct about the mass of the airplane and its acceleration, assuming a constant net force?

    Increasing the

  27. The blade of a windshield wiper moves through an angle of 90.0° in 0.398 s. The tip of the blade moves on the arc of a circle that has a radius of 0.352 m. What is the magnitude of the centripetal acceleration of the tip of the blade?

  28. Two ice skaters want to prove conservation of momentum. Skater A has a mass of 72 kg, and skater B has a mass of 48 kg. They are originally at rest. They hold hands and face each other. They then push off each other and move in opposite directions. Skater

  29. a 330 kg piano slides 3.6 m down a 28 degree incline and is kept from accelerating by a man who is pushing back on it parallel to the incline. the effective coefficient of kinetic froction is 0.4. calculate

    a) the force exerted by the man, b)the work done

  30. A man can throw a ball a maximum horizontal

    distance of 97.8 m. The acceleration of gravity is 9.8 m/s2 . How far can he throw the same ball verti- cally upward with the same initial speed? Answer in units of m.

  31. both chloroplasts and mitochondria are like in that they both have_______ membranes and their own _____.

  32. A spring scale shows a net force of 0.8 N acting on a 1.5-kg mass. What happens to the acceleration of the object if the net force is decreased to 0.2 N?(1 point)

    The acceleration increases to four times its original value, or about 0.13 m/s2. The

  33. 10. A cannon elevated at an angle of 35º to the

    horizontal fires a cannonball, which travels the path shown in the diagram below. [Neglect air resistance and assume the ball lands at the same height above the ground from which it was launched.] If the ball

  34. A cable is lifting a construction worker and a crate, as the drawing shows. The weights of the worker and crate are 833 N and 1380 N, respectively. The acceleration of the cable is 0.620 m/s2, upward. What is the tension in the cable (a) below the worker

  35. A stone is suspended from the free end of a wire that is wrapped around the outer rim of a pulley, as shown in the figure (see the figure ). The pulley is a uniform disk with mass 10.4 and radius 51.0 and turns on frictionless bearings. You measure that

  36. Both drawings show the same square, each of which has a side of length L = 0.86 m. An observer O is stationed at one corner of each square. Two loudspeakers are located at corners of the square, as in either drawing 1 or drawing 2. The speakers produce the

  37. If the net force of a system is a non-zero constant and the mass decreases, what must be true about the acceleration?

    The acceleration decreases. The acceleration increases. The acceleration is a non-zero constant. The acceleration is zero

  38. Which situation best represents a closed environment?

    two balls colliding in deep space two balls colliding on a pool table two balls colliding in midair two balls colliding under water

  39. Wave Application Quick Check

    1.) A wave travels at 1,500 m/s with a frequency of 5 hertz. What is its wavelength? -300m- 2.) Humans can hear thunder at different frequencies. These correspond to wavelengths ranging from 2.75 to 16.5 meters. If the speed of

  40. The staples inside a stapler are kept in place by a spring with a relaxed length of 0.115 m. If the spring constant is 51.0 N/m, how much elastic potential energy is stored in the spring when its length is 0.150 m?

  41. A mass m at the end of a spring vibrates with a frequency of 0.87 Hz. When an additional 602 g mass is added to m, the frequency is 0.59 Hz. What is the value of m?

  42. A stereo speaker represented by P in Figure 13-22 emits sound waves with a power output of 130.0 W. What is the intensity of the sound waves at point x when r = 7.8 m? W/m2

  43. Suppose a 65-kg boy and a 45-kg girl use a massless rope in a tug-of-war on an icy, resistance-free surface. If the acceleration of the girl toward the boy is 3.0 m/s2, find the magnitude of the acceleration of the boy toward the girl.

  44. An object whose moment of inertia is 2.5 kg · m^2 experiences the torque shown in the figure below. What is the object's angular velocity at t = 1.6 s? Assume it starts from rest.

    webassign[.]net[/]knight[/]p13-21[.]gif So far, I know that that to find the

  45. Spaceship I, which contains students taking a physics exam, approaches Earth with a speed of 0.640 c, while spaceship II, which contains instructors proctoring the exam, moves away from Earth at 0.280 c, as in Figure P26.27. If the instructors in spaceship

  46. A softball having a mass of 0.25 kg is pitched at 95 km/h. By the time it reaches the plate it may have slowed 10%. neglecting gravity, estimate the average force of air resistance during a pitch. if the distance between the plate and the pitcher is about

  47. Five motorboats are being tested to see which reaches the highest velocity in the same amount of time. After graphing the acceleration versus force for each motorboat, the graph is a sloped line with a y-intercept of zero. Which statement is correct about

  48. What average force is required to stop an 1100-kg car in 8.0 s if it is traveling at 95 km/h?

    i got the answer to be 13062.5 N. i don't think that's right...

  49. a force of 20N compresses a spring with a spring constant of 50N/m. how much energy is stored in the spring?

  50. Find the vector components along the directions noted in parentheses.

    a. a car displaced 45degrees north of east by 10.0 km (north east) b. a duck accelerating away from a hunter at 2.0meter per second squared at an angle of 35degrees to the ground

  51. a force F is applied in horizontal to a 10kg block. the block moves at a constant speed 2m/s across a horizontal surface. the coefficient of kinetic friction between the block and the surface is 0.5. the work done by the force F in 1.5 minutes is?

  52. A cart loaded with bricks has a total mass

    of 18 kg and is pulled at constant speed by a rope. The rope is inclined at 30.4 � above the horizontal and the cart moves 21.5 m on a horizontal floor. The coefficient of kinetic friction between ground and cart

  53. An object of mass 50kg is placed on inclined plane at an angle of 30 degrees to the horizontal. The height of the plane is 250cm and it's length is 500cm. What is the workdone in moving the object down the plane?

  54. A flywheel is making 180 r.p.m. and after 20 seconds it is running at 140 r.p.m. How many revolutions

    will it make, and what time will elapse before it stops, if the retardation is uniform ?

  55. During an Apollo lunar landing mission, the command module continued to orbit the Moon at an altitude of about 58.6 km. How long did it take to go around the Moon once, in seconds?

  56. What equation gives the position as a function of time for an object with constant acceleration?

  57. A falling stone accelerates at a constant rate of 10ms^2. It is dropped from rest down a deep well and 3s later a splash is heard as it hits the water below.(1) How fast will it be moving as it hits the water? (2)What will be its average speed over the

  58. Your car rides on springs, so it will have a natural frequency of oscillation. (Figure 1) shows data for the amplitude of motion of a car driven at different frequencies. The car is driven at 24mph over a washboard road with bumps spaced 12 feet apart; the

  59. Tom the cat is chasing Jerry the mouse across a table surface 1.5 m off the floor. Jerry steps out of the way at the last second, and Tom slides off the edge of the table at a speed of 5.0 m/s. Where will Tom strike the floor, and what velocity components

  60. A 3.1 kg block initially at rest is pulled to the right along a horizontal frictionless surface by a constant horizontal force of 16.6 N. Find the speed after it has moved 3.8m.

  61. A small ball with a mass of 0.6 kg and a velocity of 12 m/s hits another ball with the same mass. The first ball stops moving, and the second ball then moves forward and hits a third ball with a mass of 0.2 kg. If the system is closed, what is the velocity

  62. when rain drops form the force of gravity pulls them toward the ground. Which statement is correct about chain of events?

    the force of gravity causes the rain drops to accelerate there is a negative correlation between gravity and rain drop information

  63. A clerk moves a box of cans down an aisle by pulling on a strap attached to the box. The clerk pulls with a force of 173.0 N at an angle of 31° with the horizontal. The box has a mass of 40 kg, and the coefficient of kinetic friction between the box and

  64. a 1.4 kg block slides across a rough surface such that it slows down with an acceleration of 1.25 m/s2. What is the coefficient of kinetic frisction between the block and the surface?

  65. Two rockets with the same mass are. Accelerated. Rocket A accelerates twice as fast as Rocket B. Which statement is correct?

    The motor in rocket A is four times as powerful as the motor and in rocket B The motor in rocket A Is twice as powerful as the motor

  66. the sensor in the torso of a crash-test dummy records the magnitude and direction of the net force acting on the dummy. if the dummy is thrown forward with a force of 130.0 N while simultaneously being hit from side with a force of 4500.0 N, what force

  67. a motorist traveling at 18m/s approaches traffic lights. when he is 30m from the stop line they turn red .it takes 0.7s before he can react by appling the breakes. the car slow down at a rate of 4.6m/s^2 how far from the stop line will he come to rest and

  68. is this right?

    a 50kg barbell can be lifted by usinga force of 180 N. what is the force of gravity on this planet? if the same barbell is lifted on earth, what minimal force is needed? -i got 3.6 for gravity of the unnamed planet; and 49 N for the minimal

  69. A spring has a force constant of 70000 N/m.

    How far must it be stretched for its potential energy to be 21 J?

  70. The path of a projectile fired at a 30 degree angle to the horizontal is best described as

    1.parabolic 2.linear 3.circular 4.hyperbolic

  71. Two forces, F1 and F2 act on the 7.00-kg block shown in the drawing. The magnitudes of the forces are F1=59.0 N and F2=33.0N. What is the horizontal acceleration (magnitude and direction) of the block? F1 makes a 70 degree angle with the horizon.

  72. A 2.0-m-tall basketball player is standing on the floor a distance d from the basket, as

    shown in the figure below. He shoots the ball at an angle of 40.0o above the horizontal with a speed of 10.67 m/s and makes the shot. The height of the basket is 3.05

  73. a 15-g bullet is fired from a rifle. it takes 2.50 * 10^-3s for the bullet to travel the length of the barrel, and it exits the barrel with a speed of 715 m/s. assuming that the acceleration of the bullet is constant, find the average net force exerted on

  74. The Speed Of Sound Quick Check

    1.) Which statement correctly compares the speed of sound in solids and gases? -The speed of sound is generally faster in solids than in gases, because solids are denser than gases.- 2.) The speed of sound through diamond is

  75. A water-skier is being pulled by a tow rope attached to a boat. As the driver pushes the throttle forward, the skier accelerates. A 71.6-kg water-skier has an initial speed of 5.8 m/s. Later, the speed increases to 11.8 m/s. Determine the work done by the

  76. You throw a 20-N rock vertically into the air from ground level. You observe that when it is 15.0 m above the ground, it is travelling at 25.0 m/s upward. Use the work-energy theorem to find a) its speed just as it left the ground; b) its maximum height.

  77. A race car moving with a constant speed of 60 m/s completes one lap around a circular track in 50 s. What is the magnitude of the acceleration of the race car?

  78. 2. At time t =0, the current to the dc motor is reversed, resulting in an angular displacement of the motor shaft given by θ = (198 rad/s)t – (24 rad/s2)t2 – (2 rad/s3)t3

    a. At what time is the angular velocity of the motor shaft zero? b. Calculate the

  79. a 5.0 kilogram block weighing 49 newtons sits on a frictionless, horizontal surface, a horizontal force of 20. calculate the magnitude of the acceleration of the block

  80. A body oscillates with simple harmonic motion along the x-axis. Its displacement varies with time according to the equation x=5 sin (PIE + PIE/3). The velocity (in m/s) of the body at t=1 second is:

  81. A 0.50 kilogram ball is thrown vertically upward with an initial kinetic energy of 25 joules. Approximately how high will the ball rise ?

  82. Digital and Analog Systems Quick Check

    1.) What kind of code is generally used for sending digital information?(1 point) -binary code 1s and 0s- 2.) Which statement describes a drawback of digital medical records over paper records?(1 point) -Digital

  83. What will be the equilibrium temperature when a 245-g block of copper at 285„aC is placed in a 145-g aluminum calorimeter cup containing 825g of water at 12.0„aC?

  84. If an object is moving at a constant velocity, which must be true?(1 point)

    Its acceleration is increasing. Its acceleration is a non-zero constant. Its acceleration in decreasing. Its acceleration is zero

  85. A 30.0-kg child sits on one end of a long uniform beam having a mass of 20.0 kg, and a 43.0-kg child sits on the other end. The beam balances when a fulcrum is placed below the beam a distance of 1.10 m from the 30.0-kg child. How long is the beam?

  86. a skater with an initial speed of 7.60m/s is gliding across the ice. air resistance is negligible. (a)the coefficient of kinetic friction between the ice and the skate blades is 0.100. find the deceleration caused by kinetic friction. (b)how far will the

  87. a drunken motorist who is moving at a constant velocity of 90 km/h passes a stationary police patrol car. The patrol car immediately gives chase at a constant acceleration and catches up with the motorist after a distance of 10 km. Calculate the time taken

  88. the speed of a train is reduced uniformly from 10 m/s to 5 m/s while covering a distance of 150 m. What is the acceleration of the train? how much farther will it travel before coming to rest, assuming the same acceleration ?

  89. A slingshot consists of a light leather cup

    attached between two rubber bands. It takes a force of 25 N to stretch the bands 1.1 cm. a) What is the equivalent spring constant of the rubber bands? Answer in units of N/m b) How much force is required to pull

  90. A truck moving at 100 km /h carries a steel girder that rest on its wooden floor. what is the minimum time in which the truck can come to a stop without the girder moving forward ? The coefficient of static friction between steel and wood is 0.5.

  91. Find the density of the earth if its mass is 6×10^3kg and radius is 6.4×10^3km

  92. A helicopter is accelerating up into the air while it is also accelerating due north. Which statement about the forces acting on the helicopter is true?

    The drag on the helicopter is directed upward and to the south. The drag on the helicopter is directed

  93. When a 58g tennis ball is served, it accelerates from rest to a speed of 45m/s. The impact with the racket gives the ball a constant acceleration over a distance of 44cm. What is the magnitude of the net force acting on the ball?

  94. A child is standing on a platform of a station.

    A train travelling at 30m/s takes 3.0 secs to pass the child.What is the length of the train. a)10m-this was my answer b)27m c)30m d)90m

  95. An explosion occurs at the end of a pier. The sound reaches the other end of the pier by traveling through three media: air, fresh water, and a slender metal handrail. The speeds of sound in air, water, and the handrail are 355, 1410, and 5380 m/s,

  96. A flask is filled with 1.53 L (L = liter) of a liquid at 92.2 °C. When the liquid is cooled to 15.1 °C, its volume is only 1.36 L, however. Neglect the contraction of the flask. What is the coefficient of volume expansion of the liquid?

  97. A 4kg block is lowered down a 37° incline a distance of 5m from point A to point B. A horizontal force (F = 10 N) is applied to the block between A and B as shown in the figure. The kinetic energy of the block at A is 10 J and at B it is 20 J. How much

  98. Someone in a car going past you at the speed of 35 m/s drops a small rock from a height of 1.5 m. How far from the point of the drop will the rock hit the ground? The acceleration due to gravity is 9.8 m/s2.

    Answer in units of m.

  99. a cylindrical storage tank has a radius of 1.05m. when filled to a height of 3.79m, it holds 13500kg of a liquid industrial solvent. what is the density?

  100. Students are using the experimental setup shown in the image in which the two ends of a string are attached to a car and to a hanger. The students conduct three trials in which they place metal discs on the hanger to manipulate the force applied to the