Laboratory work: determining the efficiency of an inclined plane
The aim is to determine the efficiency of an inclined plane and to check how it depends on the angle. Equipment: a long thin board, a clamp stand, a wooden block, a set of weights, a dynamometer, a measuring tape. Fix the board in the stand at a slope and measure its length l and height h. With the dynamometer find the weight P of the block (with its load). Then pull the block steadily, without jerks, along the board with the dynamometer and record the reading F. The useful work is Aᵤ = P·h, the total work Aₜ = F·l, and the efficiency η = Aᵤ/Aₜ·100%. Repeat at least 3 times, put the results in a table, then change the height (another angle) and measure again. Usually when the angle grows the share of friction falls and η rises. Sources of error: dynamometer accuracy, uneven pulling, the tape measure. Safety: clamp the stand firmly so the board cannot fall, use no heavy loads, and keep fingers out from between the block and the board.
In class: prepare your table (l, h, P, F, Aₜ, Aᵤ, η). Practise with sample numbers from the teacher and compare results over 3 trials. Do not release the dynamometer suddenly.