unit 5 physics

trolley experiment

• connect a trollet to a piece of string, that goes over a pulley, and is connected on the other side to a hook

• mark staring line on table using ruler, trolley always travel the same distance

• place trolley on start line, holding the hook so the string is taut, and release it, stopwatch

• add 50g, x8, repeat each one 2x

• accelerating force = weight of hook + masses attached, accelerates both the trolley and masses, so are investigating the acceleration of the system,

work done

• work is done when energy is transferred from one store to another, and when a force causes an object to move

• when a force causes an object to move through a distance, work is done on the object

• so a force does work on an object when the force causes the displacement of the object

non contact forces

magnet, electrostatic, gravitational

scalar

• temperature

• mass

• energy

• distance

• speed

• density

vector

• force

• displacement

• velocity

• acceleration

• momentum

newtons 2nd law

acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object

gear system

transmit the rotational effects of forces

driven gear larger, rotate more slowly but with a greater moment, as distance to pivot is greater

spring experiment

attach spring to the top clip and ruler to the bottom, adjust ruler so its vertical nad with its zero level with the top of the spring

velocity, circular

• object is traveling in a circular motion, object is constantly charged direction, so the velocity is constant change, however it can still be travelling at a constant speed

• change in velocity is defined as acceleration, so although the object isn’t speeding up, accelerating due to changing direction

weight definition

the force of gravity acting on an object due to gravity and mass

how to measure weight

measured using a calibrated spring balance, newtonmeter

lever

effort applied to rotate one end about the centre, opposite end is also rotated about the pivot in the same direction

contact forces

• reaction

• friction

• air resistance

• tension

• normal contact

floating and sinking works

object that’s less dense than fluid its placed in weighs less than the equivalent volume of fluid. means it displaced a volume of fluids that’s equal top its weight before its completely submerged,

denser than fluid, is unable to dispel enough fluid to displace equal weight

how does breaking work

• when a force is applied to the brakes of a vehicle, work done by the friction force between the brakes and the wheel reduce the kinetic energy of the vehicle, and the temperature of the brakes increase