Physics

The angular momentum of a system of particles is conserved

• When axis of rotation remains the same

• When no external force acts upon the system

• When no external torque acts upon the system

• When no external impulse acts upon the system

A diver in a swimming pool bends his head before diving. It

• Increases his linear velocity

• decreases his linear velocity

• Increases his moment of inertia

• Decreases his moment of inertia

What happens to the moment of inertia of a figure skater when they pull their arms in while spinning?

• It increases

• It decreases

• It remains the same

• It depends on the speed of rotation

Which of the following quantities is conserved in an isolated system with no external torques?

• Linear momentum

• Angular momentum

• Kinetic energy

• Potential energy

When a gymnast tucks in during a somersault, what happens to their rotational speed?

• It increases

• It decreases

• It remains the same

• It depends on the initial speed

A rigid body is rotating about an axis. to stop the rotation, we have to apply........

• pressure

• force

• momentum

• torque

The isotopes of a same element have:

• same mass number.

• same atomic number.

• different mass number.

• both b & c.

The central region of an atom where its neutrons and protons are is its

• nucleus

• core

• electron cloud

• centre

Photoelectric current is ………. proportional to the number of photoelectrons emitted per second.

• inversely

• directly

• first directly and then inversely

• none of these