Question

3m
b) A car having mass 700kg is moving at a speed of 90kmph. On applying brakes the speed is
reduced to 36kmph in 10 sec. Calculate
(i) the change in momentum
(ii) force applied by the brakes.​

Answer 1

Answer:

p=37800N•s , F=3780N

Step-by-step explanation:

⚡ Formula to remember:-p=mv

⚡Formula to remember:- F=p/t

Answer 2

ANSWER

Given mass of car =1000kg

u=speed=90km/hr=90×

18

5

m/sec

u=25m/sec

it have to stop in 5sec

then final velocity =0

⇒v=u+at

o=25+a×5

=a=−5m/sec

2

then the force applied by break is ma

=1000X−(5m/sec

2

)

=−5000M

force =5000N by break

distance travelled to stop the car after break is applied (s=distance)

v

2

=u

2

+2as

0=(25)

2

−2×5×s

=s=

10

(25)

2

=62.5m

work done by break =F×s

w=5000×62.5=312.5KJ