English Medium Class 9 - CBSE Question Bank Solutions for Science

During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, 3 × 10⁸m s⁻¹.

Joseph jogs from one end A to the other end B of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph’s average speeds and velocities in jogging?

1. from A to B and
2. from A to C?

Abdul, while driving to school, computes the average speed for his trip to be 20 km h⁻¹. On his return trip along the same route, there is less traffic and the average speed is 30 km h⁻¹. What is the average speed for Abdul’s trip?

What is the kinetic energy of an object?

Write an expression for the kinetic energy of an object.

The kinetic energy of an object of mass m moving with a velocity of 5 m s⁻¹ is 25 J. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?

An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.

An object of mass, m is moving with a constant velocity, v. How much work should be done on the object in order to bring the object to rest?

Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?

A freely falling object eventually stops on reaching the ground. What happens to its kinetic energy?

Certain force acting on a 20 kg mass changes its velocity from 5 m s^-1 to 2 m s^-1. Calculate the work done by the force.

Which of the following conditions will give the most benefits? Why?

Why should preventive measures and biological control methods be preferred for protecting crops?

What factors may be responsible for losses of grains during storage?

Explain any one method of crop production which ensures high yield.

How do storage grain losses occur?

Change the speed of 6 m/s into km/h.

What name is given to the speed in a specified direction ?

Name the physical quantity obtained by dividing ‘Distance travelled’ by ‘Time taken’ to travel that distance.

What do the following measure in a car ?
(a) Speedometer (b) Odometer