• The needle or stylus is an artificial sapphire or diamond with a rounded or elliptical tip. The grove is a different shape each side, one for the right hand stereo and one for the left-hand signals.The needle vibrates as it runs along the uneven groove walls, setting up electrical signals in the pick-up head. The signals are then amplified and then converted to sounds by cones (diaphragms) vibrated by electromagnets in the loudspeakers.

• When a ball is in flight, a thin layer of air clings to its surface at the front. As the air passes over the ball, it breaks away from the surface setting up turbulent eddies behind. The eddying air draws its energy from the ball, slowing it down. Dimples cause the air to cling to the surface until it is well towards the rear of the ball. When it finally breaks away a narrower stream of turbulence is created causing less drag than for a smooth ball.The dimples have another purpose as well. Since the golf ball always spins backwards when it is struck, the dimples carry air upwards over the top. The air going over the top has to travel faster than the air going underneath because of this rotation. This creates a lower pressure above than below, so the ball experiences lift which keeps it in the air longer.

• The explanation for this lies mainly in the bulb’s shape which exploits the eggshell principle. Light bulbs and eggs have a rounded profile over the whole surface. When you grip a bulb, the force you apply is transmitted in all directions away from the point of contact by the curve of the glass. This result in the force being distributed over a wide area, and no excessive stress being set up at any point.