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Physics End of year test Pt.1 - Coggle Diagram
Physics End of year test Pt.1
Introduction to forces
A force is a push or a pull that acts on an object due to the interaction with another object.
Force is measured in newtons (N).
Forces are divided into contact forces and non-contact forces.
What is a force?
You cannot see a force but you can see its effect. For example, when you apply a force to push a door open.
There are two main categories of forces - contact forces and non-contact forces.
Scalars and vectors
A physical quantity is something that can be measured. Vector quantities have both a magnitude and a direction. Vector quantities are represented using arrows. The larger the arrow the greater the magnitude of the vector. Force is an example of a vector quantity.
Quantities can be a scalar quantity or a vector quantity.
Scalar quantities only have a magnitude.
Non-contact forces
Magnetic force is experienced by a magnet or a magnetic material, eg iron, when placed in a magnetic field.
Electrostatic force is experienced by a charged particle in an electric field.
Non-contact forces act between two objects that are not physically touching.
Gravitational force is experienced by a mass when it is sufficiently close to another mass.
Contact forces
Tension is a pulling force exerted on an object by a string, rope or rod.
Friction is a force that acts between two touching surfaces and prevents or resists them moving against each other.
Contact forces act between two objects that are physically touching.
Upthrust is an upwards force that acts on an object when it is in a fluid (a liquid or gas).
When an object moves through the air it experiences air resistance. This force acts against the direction of movement.
Thrust is a driving force exerted by an engine to make an object move.
When an object pushes on a surface like a table, wall or the ground, the surface pushes back on the object with a balancing force.
Measuring Forces
Force meters have a spring inside them. The weight of the mass causes the spring to stretch.
It is important to ‘zero’ the force meter before you use it. This means adjusting it so that the reading is zero when there is no force acting on it.
A force meter, also known as a newton meter, can be used to measure the size of a force.
If you don’t ‘zero’ the force meter, all your measurements will be inaccurate by the same amount. This is called a systematic error.
Speed
Calculate speed using the speed equation - speed = distance divided by time.
The speed equation can be rearranged to find distance travelled and time taken.
Speed is a measure of how fast an object is moving.
In science, speed is typically measured in metres per second, m/s. This is the simplest unit of speed.
Objects moving in the same direction use this equation: Relative Speed = fastest speed-slowest speed
Moments
Moment = Force x Distance
Balancing moments: Step 1: Calculate the clockwise moment using the moment equation.
Step 2: The seesaw needs to be balanced. Remember - total anti-clockwise moment = total clockwise moment.
A moment is the turning effect of a force. Forces that create a moment act around a point called the pivot. The pivot is the point around which the object can rotate or turn.