Neb QnA's for science

The angular momentum of a rotating body changes from L to 4L in 3 seconds. In such condition, what torque is acting on the body?

Both "the work done by a force" and "the torque produced by a force" are the product of force and the position vector. how can one make the difference between the two? explain.

Experienced cooks can tell whether an egg is raw or hard boiled by rolling it down a slope. how is this possible? What are they looking for?

If the ice on the polar caps of the earth melts, how will it affect the duration of the day? Explain.

Can a single force applied to a body change both its translational and rotational motion? Explain.

Why spin angular velocity of a star is greatly increased when it collapses under gravitational pull and becomes a neutron star?

Two discs of same mass and thickness are made of materials having different densities. Which one of them will having different densities. Which one of them will have larger moment of inertia?

Why is hand driven grinding machine, handle is put near the circumference of the stone or wheel?

A fan with blades takes longer time to come to rest than without the blades. why

The cap of a bottle can be easily opened with the help of two fingers than with on finger. why?

A dancer girl is rotating over a turntable with her arms outstretched. If she lowers her arms, how does this affect her motion?

If angular momentum is conserved in a system, whose moment of inertia is decreased, will its rotational kinetic energy be also conserved? explain.

Explain, Why the speed of a whirl winds in a tornado is alarmingly high.

If earth contracts to half its radius, What would be the length of the day?

There are two spheres of the same mass and same radius. one is solid and the other is hollow which of them has a larger moment of inertia about a diameter?

Why is it more difficult to revolve a stone by tying it to a longer string than by tying it to a shorter string?

Why a wrench of longer arm is referred in comparison to a wrench of shorter arm?

Does the angular momentum of a body moving in a circular path change? Give explanation to your answer.

If a body is rotating, is it necessarily being acted upon by an external torque?

The angular velocity of the earth around the sun increases when it comes closer to the sun. why?

Why are there two propellers in a helicopter?

If the earth is struck by meteorites, the earth will slow down. why?

Why are spokes fitted in the cycle wheel?

A man standing on the turn table extends his hands suddenly. What happens?

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