Physics - Topic 2 - Mechanics

suggest why the two values for the average velocity differ.

• the velocities are not instantaneous

• the acceleration may have not been uniform

it is suggested that the experiment would be better performed from an upper storey of a tall building. explain the advantages and disadvantages of such a change

• the time is much longer so the percentage uncertainty will be smaller

• high speeds could lead to air resistance affecting the motion (air resistance is agains

a coin is projected horizontally from a table top at the same time as an identical coin is dropped from the same point. explain why they both strike the floor at the same time.

horizontal and vertical components of the velocity are independent. in the vertical plane, both coins will accelerate downwards at 9.81m/s² over the same vertical displacement.

state what is meant by equilibrium

• zero resultant force (in any direction)

• zero turning moment (about any point)

state what is meant by the centre of gravity of an object

the point through/at which the weight of the object may be taken to act

state what is meant by the moment of a force about a point

moment of a force (around a point) = force × perpendicualr distance (to line of action of the force from the point)

core practical 1: describe an experiment to measure the acceleration of a free-falling object.

• initial acceleration due to a resultant force

• decreasing acceleration as resistive forces increase

• no acceleration as resultant force is zero

• need to neglect frictional forces to assume constant speed over 1 second interval used to calculate previous answer