Question

A truck covers 32.0 m in 8.70 s while smoothly slowing down to final speed of 2.10 m/s. (a) Find its original speed. Incorrect: Your answer is incorrect. Does it make sense in this problem that the initial velocity is smaller than the final velocity? m/s (b) Find its acceleration. (Indicate the direction of the acceleration with the sign of your answer.)

Answer 1

Step-by-step explanation:

Given that,

Distance covered, d = 32 m

Time, t = 8.7 m

Final speed of the truck, v = 2.1 m/s

(a) Let a is the acceleration and u is the original speed of the truck.

Using first equation of kinematics as :

`v=u+at`

`2.1=u+8.7a`..............(1)

Using second equation of kinematics as :

`d=ut+(1)/(2)at^2`

`32=u(8.7)+(1)/(2)a(8.7)^2`...........(2)

On solving equation (1) and (2) we get :

Original speed,
`u=5.25\ m/s`

(b) Acceleration,
`a=-0.36\ m/s^2`

Hence, this is the required solution.