Secondary School (English Medium) (5 to 8) Class 8 - CBSE Question Bank Solutions

In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in case.

Squeezing a piece of lemon between the fingers to extract its juice.

In the following situation identify the agent exerting the force and the object on which it acts. State the effect of the force in case.

Taking out paste from a toothpaste tube.

In the following situation identify the agent exerting the force and the object on which it acts. State the effect of the force in case.

A load suspended from a spring while its other end is on a hook fixed to a wall.

In the following situation identify the agent exerting the force and the object on which it acts. State the effect of the force in case.

An athlete making a high jump to clear the bar at a certain height.

Friction opposes the ______ between the surfaces in contact with each other.

Friction depends on the ______ of surfaces.

Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.

Explain why sportsmen use shoes with spikes.

Give examples to show that friction is both a friend and a foe.

Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?

Most liquids that conduct electricity are solutions of ________, _______ and ________.

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

The bulb does not glow in the setup shown in figure list the possible reasons. Explain your answer.

A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that ______.

Does pure water conduct electricity? If not, what can we do to make it conducting?

In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.

A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?

Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.

Paheli had heard that rainwater is as good as distilled water. So, she collected some rain water in a clean glass tumbler and tested it using a tester. To her surprise, she found that the compass needle showed deflection. What could be the reasons?

When a glass rod is rubbed with a piece of silk cloth the rod ______.