Question

A car starts from rest and attains a velocity of 36 km/h in 40 s. The driver applies brakes and slows down the car to 5m/s in 10 s. Find the acceleration of the car in both the cases.
Solution:
Hint: 1 km/h = 5/18 m/s
Case 1:
Initial velocity, u= _________
Final velocity, v = __________
Time t = __________

Acceleration, a = (v-u)/t

= ___________

Case 2:
Initial velocity, u= _________
Final velocity, v = __________
Time t = __________

Acceleration, a = (v-u)/t

= ___________

Answer 1

Answer:

In first case the acceleration is 1/4m/s.s.

Explanation:u=0m/s

v=36km/h

in m/s

=36×1000/1×3600

=36000/3600

=10m/s

t=40s

a=(v-u)/t

=(10-0)/40

=10-0/40

=10/40

=1/4m/s.s.

Answer:In second case the acceleration is -1/2m/s.s.

Explanation:u=10m/s

v=5m/s

t=10s

a=(v-u)/t

=(5-10)/10

=5-10/10

=-5/10

-1/2m/s.s.