9th Class (CBSE) Science: Motion

Question: A train is travelling at a speed of 90 km h^-1 . Brakes are applied so as to produce a uniform acceleration of – 0.5 ms^-2 . Find how far the train will go before it is brought to rest.

Answer:

Question: A trolley, while going down an inclined plane, has acceleration of 2 cm s^-2 . What will be its velocity 3 s after the start?

Answer:

a = 2 cm/s^-2 
t = 3 s
v = ?
u = 0
v = u + at
= 0 + 2 × 3
v = 6 cm/s.

The velocity of a trolley 3 s after the start will be 6 cm/s.

Question: A racing car has a uniform acceleration of 4 ms^-2 . What distance will it cover in 10 s after start?

Answer:

Question: A stone is thrown in a vertically upward direction with a velocity of 5 ms^-1. If the acceleration of the stone during its motion is 10 ms^-2  in the downward direction, what will be the height attained by the stone and how much time will it take to reach there?

Answer:

The height attained by the stone is 1.25 m and time required to reach there is 0.5 s.

Question: An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?

Answer: