Motions Forces and Energy

Distance travelled per unit time V = s / t v = ms-1 s = distance in m t = time in s

Average speed = total distance travelled / total time taken

Calculate the area under the line.

Increase in speed per unit time Decceleration: decrease in speed per unit time. A(ms-2) = △v / △t △v = change in speed (ms-1) △t = change in time (s)

Constant acceleration of 9.8 ms -2

Mass is a measure of the quantity of matter in an object

Weight is the gravitational force on an object that has mass.

The gravitational force acting on an object per unit mass. g = W / m W = weight of object in Newtons m = mass of object in kg

9.8N / kg

Gravitational field strength = acceleration of free fall

Amount of mass per unit volume. ρ = m / v ρ = density: g / cm cubed or kg / m cubed m = g / kg v = cm cubed / metres cubed

• Measure the mass of a measuring cylinder • Add liquid into the measuring cylinder and record its volume • Measure the mass of the measuring cylinder with the liquid • Find mass of liquid by subtracting the mass of the measuring cylinder with the liquid from the one without the liquid. • Calculate density using ρ = m / v

• Measure the mass of the object using a scale • Use a measuring cylinder large enough to hold the object • Fill the measuring cylinder so the obejct will be completely submerged • Measure the volume of liquid • Add the object carefully and read the new volume • Subtract the liquid with the objects volume from the original volume • Calculate density using ρ = m / v

Forces can change the speed, direction or shape of an object Forces are measured in Newtons

Force between two surfaces that may impede relative motion and produce heating.

Drag affects objects moving through liquids and gasses. Drag in air = air resistance

Object either remains stationary or at a constant speed.

F = m x a F = force in newtons m = mass in kg a = acceleration in ms-2

acceleration

Kinetic energy, gravitational potential energy, chemical energy, elastic energy, nuclear energy, electrostatic energy and internal (thermal) energy.

Mechanical work done - When a force moves an object a distance Electrical work done - Charges move due to a potential difference Heating - Due to temperature difference caused electrically or from chemical reaction. Waves - Electromagnetic radiation, sound, other waves.

Ek = 1 / 2 x m x v² Units - Joules mass - kg speed - ms-1

△Ep = m x g x △h Measured in joules m - kg △h - metres g - gravity 9.8ms-2

• Fuel is burned to produce steam in a boiler • Steam turns a turbine • Turbine drives a generator • Generator produces electricity for homes