Physic

• The second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
• Speed is defined as the distance moved divided by the time taken.
• Average speed is calculated by adding the distance moved and the time taken and dividing by two.
• Speed is measured in metres per second (m/s).
• Velocity is the speed in a given direction.
• Acceleration is the rate at which an object increases speed or velocity.
• Acceleration is calculated by subtracting the initial velocity from the final velocity and dividing by the time taken.
• Acceleration is measured in metres per second per second (m/s/s) or metres per second (m/s).
• A drag car increases its velocity from zero to 60m/s in 3s with an acceleration of 20m/s^2.
• A ball is dropped with an acceleration of 10 m/s for 12s, by how much will the velocity of the ball change?
• A rocket speeds up from 1 000 m/s to 5 000 m/s in 2s with an acceleration of 2000 m/s^2.
• In 6s the car gains an extra 24m/s.
• Deceleration is negative acceleration, the object is slowing down.
• How much time did this change take?
• Constant acceleration example: A car passes point A with a velocity of 10m/s and a steady (constant) acceleration of 4m/s.
• A biker speeds up from 0 to 10 m/s in 5s with an acceleration of 10 m/s.
• Final velocity = initial velocity + extra velocity.
• A car speeds up from 10 to 20 m/s with an acceleration of 2 m/s.
• The mass of an object depends on how much matter there is in the object.
• The greater the mass of an object, the greater its weight.
• The weight of an object depends on its mass and gravity.
• The SI unit of weight is Newton (N).
• The SI unit of mass is the Kilogram (Kg).
• Using a Newtonmeter to weight an object.
• The object can be solid, liquid or gas.
• Two masses of the same mass contain the same amount of matter.
• The mass of a body is a measure of the amount of matter it contains.
• Two masses of different mass contain different amount of matter.
• Acceleration = 20 - 0 = 2m/s.
• Acceleration = 0 (no change in velocity).
• On a velocity – time (or speed – time) graph, the area under the line is numerically equal to the distance travelled.
• The area of a triangle is ½ x base x height.
• The acceleration for each of the 4 sections of the velocity-time graph can be calculated.
• The area under the line on a velocity – time (or speed – time) graph is numerically equal to the distance travelled.
• The total distance travelled on a velocity – time (or speed – time) graph is 1700m.
• Acceleration can be calculated by the gradient of a velocity:time graph.
• Acceleration = 0 - 60 = -3m/s.
• The record the results of an experiment to stretch a spring.
• At the elastic limit in Hooke’s Law, the spring behaves in a ‘plastic’ way and does not return to its original length – it is permanently stretched.
• Hooke discovered that the amount a spring stretches is proportional to the amount of force applied to it.