A bob of mass 0.50 kg is suspended from the end of a piece of string 0.45 m long. 

The bob is rotated in a vertical circle at a constant rate of 120 revolutions per minute.

What is the tension in the string when the bob is at the bottom of the circle?

A string passes through a smooth thin tube. Masses m and M are attached to the ends of the string. The tube is moved so that the mass m travels in a horizontalcircle of constant radius r and at constant speed v.

Which of the following expressions is equal to M ?

What is the angular speed of a satellite in a geostationary orbit around the Earth?

Satellites N and F have the same mass and are in circular orbits about the same planet. 

The orbital radius of F is greater than that of N.

Which is greater for F than for N?

An object of mass m moves in a circle of radius r. It completes n revolutions every second.

What is the kinetic energy of the object?

A particle travels in a straight line with speed v.

The particle slows down and changes direction. The new speed of the particle is $\frac{v}{2}$ .

The new velocity has a component of $\frac{v}{4}$ in the same direction as the initial path of the particle.

Through which angle has the particle turned?

The diagram shows two points P and Q which lie 90° apart on a circle of radius r.

A positive point charge at the centre of the circle creates an electric field of magnitude E at both P

and Q.

Which expression gives the work done in moving a unit positive charge from P to Q?