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What is gravitational potential and how can gravitational potential energy be used to estimate the escape velocity of a planet of mass m and radius r?

The graviational potential at a point in space is the work done to move a unit mass from infinite (very far away) to the point in question. The gravitational potential V at a point outside a single spherical...
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An object is let in free fall from a platform 20m high above Earth's surface. Describe the event in terms of energy and thus determine the speed of the object when it hits ground. Air resistance is negligible and gravitational acceleration is constant.

When the object is at rest on the platform it has no kinetic energy, but only potential energy. The potential energy is m g h where m is the mass of the object, g the gravitational acceleration and h the hei...
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Why does an α particle cause more ionisation than a β particle if they have the same kinetic energy?

An alpha particle has a much larger volume than a β particle, so when passing by an atom it is more likely to collide with an electron and knock it out of the atom causing the atom to be ionised (meaning it ...
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How do you work out the work out the current through resistors in parallel?

[I would use the whiteboard to draw diagrams as I was talking] A good analogy for circuits is that of water pipes. The wires are nice wide pipes with no resistance to flow. Resistors are sections of narrow p...
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A car is travelling at 20 m/s. The accelerator is applied, causing an acceleration of 2m/s^s. How fast is the car travelling after 10 seconds of acceleration?

Using the SUVAT equation: v = u + at v = ?u = 20a = 2t = 10 v = 40m/s
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