# physics

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

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.

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

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

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.

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

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

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

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...

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

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

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 ?

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

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

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

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

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

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

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

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

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

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

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