Question

a train moving with a velocity of 25 m/s. it is brought to rest by applying brakes which produce a uniform retardation of 0.5m/s square calculate (1)velocity of train after 10 secs(2)if the mass of train is 20000 kg then calculate the force required to stop the train​

Answer 1

(i) So, we have t = 10 s

a = - 0.5 m/s² and u = 25 m/s

⇒v = u + at

⇒v = 25 + (-0.5)(10)

⇒v = 25 - 5 = 20 m/s

Speed of train after 10 s is 20 m/s

(ii) Since we know that,

⇒F = ma

Where we have m = 20,000 kg and a = 0.5 m/s²

⇒So, F = (20,000)(-0.5) kg m/s²

⇒F = - 10,000 N

Negative sign shows that force will be applied against direction of motion.

Force required to stop train is 10,000 N.

Answer 2

1.u=25m/s

a= -0.5m/s²

t=10s

v=?

v=u+at

v=25-5=20m/s

2. m=20000kg

f=ma

f=20000×-0.5

f= 1000N