Question

A car is accelerated from rest to 85 km/h in 10 s. Would the energy transferred to the car be different if it were accelerated to the same speed in 5 s?

Answer 1

Answer:

acceleration =a

final velocity =v

time =t

initial velocity =u

a1=v-u/t

=85-0/10=85/10

=8.5m/s

a2=v-u/t

=85-0/5

=85/5=17

change in accleration =17-8.5=8.5

Answer 2

Given: A car is accelerated from rest to 85 km/h in 10 s.

To find: If the energy transferred to the car would be different if it were accelerated to the same speed in 5 s.

Solution:

• In order to solve the given question, the velocity of 85 km/h has to be converted into km/s.

        $85 km/h = \frac{85}{3600} km/s$

• Acceleration is the change in velocity with respect to time and its formula is given as,

        $a = \frac{v}{t}$

• If the car was accelerated in 10 seconds, then the acceleration would be calculated as,

        $a_{1} = \frac{85}{3600 * 10}$

             $= 0.002 ms^{-2}$

• If the car was accelerated in 5 seconds, then the acceleration would be calculated as,

        $a_{2} = \frac{85}{3600 * 5}$

             $= 0.005ms^{-2}$

• The acceleration in the second is greater than the acceleration in the first case, so the energy transferred to the car is different.

Therefore, yes, the energy transferred to the car would be different if it were accelerated to the same speed in 5 s.