M.7(1) - COIN AND FEATHER TUBE

It is used to demonstrate free fall in a vacuum. It shows the coin and the feather falling with the same acceleration and striking the tube's bottom at the same time. The apparatus consists of a glass tube 1 m long and 4.5 cm in diameter with brass caps, stopcock at one end, and supported on a tripod. The vacuum pump is connected to the hose connector in the base. Evacuate the tube, close off the stopcock and remove the hose. The apparatus can be spinned around its support arm. The coin and feather will fall at the same rate. Very occasionally the feather sticks at one and and must be dislodged by shaking the apparatus.

M.7(2) - ATWOOD MACHINE

it has a ball-bearing pulley on an upright support mounted on a tall stand. A cord carrying mass holder passes over the pulley. Different masses are provided for attachment to the mass holders. Together, they form a constant mass system. One of the mass holders is kept slightly heavier. This holder is then released from near the top and falls pulling the cord over the pulley behind it. Acceleration is determined by measuring the time taken for the heavier mass to reach a certain point at the bottom of the stand.

M.7(3) - FALLING BODY EXPERIMENT

The apparatus consists of a tall stand with an electromagnet attached on the upper end and close to the floor, directly beneath the electromagnet, a switch plate that activates the clock when hit by the falling steel ball. The electromagnet is powered by a 6 VDC power supply. Better measurements are obtained when the adjustment of the power supply is such that the electromagnet barely holds the steel ball while the circuit is closed. A small button (switch K) on the side of the switch plate (switch L) sets it up for successive measurements and initiates each experiment. Thus, when switch K is thrown to position B, the clock is activated and the circuit is broken, causing the electromagnet to release the ball. When the ball reaches switch L, the clock stops.

M.7(4) - HINGED STICK AND FALLING BALL

The free end of a falling hinged stick (a narrow board) falls faster than a free-falling ball placed at the other end of the stick, when their center of masses accelerate at an equal rate.

The apparatus is one meter long and consists of two wooden boards mounted one above the other and hinged together at one end. Near the other end of the top board there is a clear plastic cup and at the very tip of the board, a small support for a steel ball. With the apparatus on a flat surface, hold the upper board at about 45°. Set the ball on the support and let the board go.

Surprisingly, the ball will end up in the plastic cup, when the two boards are sitting together. It can also be tried with a plastic ball to show that this works regardless of the ball's mass.