Question

A car has a total mass of 900 kg and is travelling at 20 m/s .at time t=0,the driver sees an accident applies the brakes at t=0.60s to stop the car. after the brakes are applied , the car comes to rest in a further 4.0 s. 2 points grading comment: i) calculate the deceleration of the car as it brakes.

Answer 1

To find the deceleration of the car, we use the kinematic equation ‘v = u + at’ and solve for ‘a’. With the given values, the deceleration is calculated to be 5 m/s², which indicates the car is slowing down.

Step-by-step explanation:

To calculate the deceleration of the car, we can use the following kinematic equation:

v = u + at

where v is the final velocity (0 m/s, since the car comes to rest), u is the initial velocity (20 m/s), a is the acceleration (deceleration in this case, which is what we want to find), and t is the time taken for the car to come to stop (4 s).

Rearrange the equation to solve for acceleration:

a = (v - u) / t

Substitute the known values:

a = (0 m/s - 20 m/s) / 4 s

a = -20 m/s / 4 s

a = -5 m/s²

The negative sign indicates that the acceleration is in the opposite direction to the motion of the car, hence it is a deceleration. So, the deceleration of the car is 5 m/s².