A car of mass 1000kg moving at 25mls
is brought to rest over a the time
required to stop the car is.
Answers
Answer:
Given:
Mass m = 1000 kg; Initial velocity u = 25m/s; final velocity v = 0 m/s (since the car is coming to rest, hence v =0)
Distance = 50 metres.
To find : Force required to stop the car AND the time required to stop it.
Solution:
We know, Force = Mass * Acceleration
We have mass given to us. Hence we need to find Acceleration.
Applying Newton's IIIrd law of motion, v2= u2 + 2as
Substituting values,
0 = (25)2 + 2 * a * 50
0 = 625 + 100a
-625 = 100a
a = -6.25 m/s2
That is, retardation = 6.25 m/s2
Now we can calculate force. Force = Mass * Acc. = 1000 * 6.25 = 6250 N
(Here we neglected the negative sign of Acceleration because we know the braking force is acting in an opposite direction.
To calculate time, we can use Newton's 1st law of motion, v = u + at
0 = 25 + (-6.25)t
- 25 = -6.25t
25 = 6.25t
t = 4 seconds.
Explanation: