A car of mass 1200kg travelling at 72km/h was brought to rest in 4 seconds.
1. what is this period in m/s?
2. find;
a. the deceleration of the car.
b. the force that caused the car to come to rest.
c.the distance it travelled during its deceleration.
1. 72km/h = 72000m/3600s = 20 m/s.
2a. V2 = V1 + a*t.
0 = 20 + a*4,
a = -5 m/s^2 = deceleration.
2b. F = M*a = 1200 * (-5) = -6000 N.
The negative sign means the force opposes the motion.
2c. V2^2 = V1^2 + 2a*d.
0 = 20 - 10d,
d = 2m.
12
what is physics
To answer the given questions, we'll need to convert the given values to appropriate units and apply relevant equations of motion.
1. To convert km/h to m/s, divide the value by 3.6. So, 72 km/h is equivalent to 20 m/s.
2. a. The deceleration of the car can be calculated using the equation:
acceleration = change in velocity / time
Here, the initial velocity is 20 m/s (calculated in the previous step), and the final velocity is 0 m/s (since the car came to rest). The time is given as 4 seconds.
So, the deceleration can be calculated as:
acceleration = (0 - 20) m/s / 4 s = -5 m/s²
b. The force that caused the car to come to rest can be calculated using Newton's second law of motion:
force = mass x acceleration
Given mass of the car is 1200 kg, and previously calculated acceleration is -5 m/s² (negative sign indicates deceleration):
force = 1200 kg x -5 m/s² = -6000 N
The negative sign indicates that the force is in the opposite direction to the motion of the car.
c. To calculate the distance traveled during the deceleration, we'll use the equation of motion:
distance = (initial velocity + final velocity) / 2 x time
Here, the initial velocity is 20 m/s, final velocity is 0 m/s, and time is given as 4 seconds.
distance = (20 m/s + 0 m/s) / 2 x 4 s = 10 m/s x 4 s = 40 meters
Therefore, the answers are:
1. The period of 72 km/h is equivalent to 20 m/s.
2. a. The deceleration of the car is -5 m/s².
b. The force that caused the car to come to rest is -6000 N.
c. The distance traveled during the deceleration is 40 meters.
1 km/hr = 20 m/s
periods are not measured in m/s
a = (-20m/s)/(4s) = -5 m/s^2
F = ma
s = 1/2 at^2
...
2c. Correction:
0 = 20^2 - 10d,
d = 40 m.