Advertisements
Advertisements
Question
A truck running at 90 kmh−1, is brought to rest over a distance of 25 m. Calculate the retardation and time for which brakes are applied.
Advertisements
Solution
Initial velocity = u = 90 kmh−1 = `90xx5/18` ms−1
u = 25 ms−1
Final velocity = v = 0
Distance = S = 25 m
v2 − u2 = 2aS
(0)2 − (25)2 = 2a (25)
50a = −625
(retardation) a = `(-625)/50` = −12.5 ms−2
Now, v = u + at
0 = 25 + (−12.5)t
12.5t = 25
(Time) t = `25/12.5` = 2s
APPEARS IN
RELATED QUESTIONS
A vehicle is accelerating on a straight road. Its velocity at any instant is 30 km/h. After 2 s, it is 33.6 km/h, and after further 2 s, it is 37.2 km/h. Find the acceleration of the vehicle in m s-2. Is the acceleration uniform?
Give an example of an accelerated body, moving with a uniform speed.
A motor bike running at 5 ms−1, picks up a velocity of 30 ms−1 in 5s. Calculate
- acceleration
- distance covered during acceleration.
Define acceleration.
The acceleration of a moving body is constant in magnitude and direction. Must the path of the body be a straight line?
If not, given an example.
The distance covered by a body is directly proportional to the square of the time elapsed. What can you say about its acceleration?
Is it possible for an accelerating body to have constant speed?
The rate of change of velocity is ______.
Correct your friend who says that acceleration gives the idea of how fast the position changes.
