OCR physics B21C – P2
Gas Pressure is created when gas particles collide with the walls of their container. The more often the particles collide with the walls, and the faster they are moving, the greater the pressure.
Forces can cause an object to rotate and the turning effect of the force is called a moment. If a resultant force acts on an object about a fixed turning point called the pivot or fulcrum it will cause the object to rotate e.g. using a spanner, a screwdriver, opening a door hanging on hinges.
When a force acts on a spring it is stretched or compressed, its length will changes by an amount e from its original length.
Pressure can be calculated if you know the force applied to or by an object and the contact area. The units are newtons per square meter, or N/m2.
An object of constant mass accelerates in proportion to the force applied.
In physics, the kinetic energy (KE) of an object is the energy that it has due to its motion. It is defined as the work needed for an object of a known mass to accelerate to a given velocity.
Specific heat capacity is how much heat energy is required to raise 1 kg of a substance by 1 °C.
The quantity power is the rate at which work is done. The quicker work is done the greater the power.
Stretching or squashing an object can transfer energy into its elastic potential energy store.
The size of the current is the rate of flow of charge. Electrons are negatively charged particles which transfer energy through wires as electricity.
Resistance is an electrical quantity that measures how a device or material reduces the electrical current flow through it.
The power of an appliance is the energy that is transferred per second. Electric power is the rate, per unit time at which electrical energy is transferred by an electric circuit.
Density is a measure of how compact the particles are in a substance. Density is defined as the mass per unit volume.
Specific latent heat is the energy needed to change the state of a substance.
The radioactivity of a sample decreases over time. Half life is a measurement of this decrease.
Lifting an object in a gravitational field transfers energy into the objects gravitational energy store. Gravitational potential energy is the energy an object has due to its height above Earth.
The efficiency of a device is the proportion of input energy that is converted to useful energy.
The potential difference between two points is the energy transferred per unit charge. An electrical circuit is an energy transformation device.
The unit for work done is the joule (J), or Newton meter (N-m). One joule is equal to the amount of work that is done when 1 N of force moves an object over a distance of 1 m.
All moving objects have momentum. Forces can cause changes in momentum. The total momentum in a collision or explosion is conserved and stays the same. Car safety features absorb energy involved in a crash they slow down the collision thus reducing the force of impact.
A transformer is an piece of electrical apparatus which will increase or decrease the voltage in an alternating current. It can be designed to “step up” or “step down” voltages and is based on the magnetic induction principle.
A current-carrying wire or coil can exert a force on a permanent magnet. The force increases if the strength of the magnetic field and/or current increases. This is called the motor effect.
Uniform or constant acceleration is a type of motion in which the velocity of an object changes by an equal amount in every equal time period.
Fluid pressure is exerted on the surface of an object in a liquid. This pressure causes upthrust . An object placed in a liquid will begin to sink. As it sinks, the liquid pressure on it increases and so the upthrust increases.
Acceleration is how quickly the velocity is changing whether it be speed, direction or both. Acceleration is a measure of how quickly the velocity of an object is changing.
Speed is how fast an object is moving in no given direction. Velocity is how fast an object is moving in a given direction. In physics, you can calculate the average speed by taking the total distance travelled and dividing it by the total time required to travel that distance.
Weight is the force acting on an object due to gravity. The weight of an object is defined as the force of gravity on the object and can be calculated as the mass times the acceleration due to gravity.
Weight is the force acting on an object due to gravity. The weight of an object can be defined as the force of gravity on the object. Since the weight is a force, its unit is the Newton.
