Advertisements
Advertisements
Question
A bus was moving with a speed of 54 km/h. On applying brakes it stopped in 8 seconds. Calculate the acceleration.
Advertisements
Solution
(b) We have to find the value of uniform acceleration. So, Initial velocity
(u) = 54 km/hr
= `"54(1000)"/3600` m/s
= 15 m/s
Final velocity (v) = 0 m/s
Time taken(t) = 8 s
So acceleration, `a = (v-u)/t`
Put the values in the above equation to get the value of acceleration
`a = (0-15)/8`
= -`1.875 "m/s"^2`
APPEARS IN
RELATED QUESTIONS
Give one example of a situation in which a body has a certain average speed but its average velocity is zero.
Explain why, the motion of a body which is moving with constant speed in a circular path is said to be accelerated.
A motorcycle moving with a speed of 5 m/s is subjected to an acceleration of 0.2 m/s2. Calculate the speed of the motorcycle after 10 seconds, and the distance travelled in this time.
A cheetah starts from, rest, and accelerates at 2 m/s2 for 10 seconds. Calculate :
(a) the final velocity
(b) the distance travelled.
Derive the formula s= `ut+1/2at^2` , where the symbols have usual meanings.
The slope of a speed-time graph gives:
The figure shows the displacement - time graph for four bodies A, B C and D. In each case state what information do you get about the acceleration (zero, positive or negative).
Multiple choice Question. Select the correct option.
The speed of a car reduces from 15 m/s to 5 m/s over a displacement of 10 m. The uniform acceleration of the car is :
Can you suggest a real-life example about the motion of a body from the following velocity – time graph?
A packet is dropped from a stationary helicopter, hovering at a height ‘h’ from ground level, reaches the ground in 12s. Calculate
- the value of h
- final velocity of packet on reaching the ground. (Take g = 9.8 ms−2)
