Question

A train accelerates from 40 km/h to 58km/h in 10 sec. (i) Acceleration (ii) The distance travelled by car.

Answer 1

EXPLANATION.

• GIVEN

A train accelerates from 40 km/hr to 58 km/hr

Time = 10 seconds.

TO FIND.

1) = Acceleration.

2) = The distance travelled by car.

According to the question,

initial velocity = u = 40 km/hr

=> 40 X 5/18 = 100/9 m/s

final velocity = v = 58 km/hr

=> 58 X 5/18 = 145/9 m/s

Time = 10 seconds.

From newton first equation of

kinematics.

=> v = u + at

=> 145/9 = 100/9 + 10a

=> 145/9 - 100/9 = 10a

=> 45/9 = 10a

=> 5 = 10a

=> a = 5/10 = 0.5 m/s²

From newton second equation of

kinematics.

=> s = ut + ½at²

=> s = 100/9 X 10 + ½ X ½ X 10 X 10

=> s = 1000/9 + 25

=> s = 1000 + 225 / 9

=> s = 1225 / 9

=> s = 136.1 m

Therefore,

1) = Acceleration = 0.5 m/s²

2) = Distance travelled = 136.1 m