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:
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.