Year 7 - Science - Physics

Force

A push, pull, or twist

Contact Force

A force that requires contact to act on an object

Non-contact force

A force that does not require contact to act on an object

6 Types of Contact Forces

Normal force

Applied force

Tension force

Frictional force

Air resistance

Spring force

3 Types of Non-Contact forces

Gravitational Force

Magnetic Force

Electrical (Electromagnetic) Force

Balanced force

Equal in size and opposite in direction. There is no change in motion.

Unbalanced force

Forces applied to an object in opposite in directions that are not equal in size. Result in a change in motion.

Motion

The change in position of an object with respect to its surroundings in a given interval of time.

Constant Speed

Speed maintained consistently over time. The acceleration of the object is 0.

Acceleration

Where velocity changes

Inertia

The resistance to change

Energy

The ability to do work

Friction

A force that resists the sliding or rolling of one solid object over another when two objects rub against each other.

Weight

The gravitational force with which the Earth attracts the masses towards the center. Measured in N (Newtons)

Mass

The amount of matter something takes up. Measured in kg or g.

Net Force

The sum of all forces acting on an object in a single plane.

Simple Machine

A mechanical device that changes the direction or magnitude of a force

6 Types of Simple Machines

Pulley

Lever

Wheel and Axle

Wedge

Screw

Inclined Plane

Work

Motion caused by a force. Force x Distance. Measured in J (Joules)

Parts of a Lever

Fulcrum, load, effort

Lever

A simple machine consisting of a beam pivoted at a fixed hinge, or fulcrum.

Inclined Plane

A flat supporting surface tilted at an angle from the vertical direction, with one end higher than the other. Used as an aid for raising or lowering a load.

Wedge

A triangular tool, that is thick on one end and tapers to a thin or sharp edge on the other end. Changes either the magnitude or direction of a force.

Mechanical Advantage

A way of making work easier by using tools or machines. It helps you lift heavy things or move them with less effort

Force Multiplier

Effort arm is longer than the load arm. Mechanical advantage is greater than 1.

Speed Multiplier

Load arm is longer than effort arm. Mechanical advantage is less than 1.

Buoyancy

The tendency of an object to float or to rise in a fluid when submerged. This fluid can be either a liquid or gas.

Density

The quantity of something per unit volume, unit area, or unit length.

Archimedes’ Principle

The buoyant force is equal to the weight of the displaced water

Ways to Increase Friction

Make surfaces rougher

Increasing the force pushing the surfaces together

More contact area

Ways to decrease friction

Add lubricants

Make surfaces smoother

Decreasing the force pushing the surfaces together

Less contact area

Distance

How far something travels. Measured in metres.

Time

How long something takes to happen. Measured in seconds, minutes, or hours

Speed

How fast something moves. Distance ➗ Time

Newton’s first law of motion

Law of Inertia. An object in motion will stay in motion. An object at rest will stay at rest, unless acted upon an outside, unbalanced force.

Newton’s second law of motion

Law of Acceleration. Acceleration is produced when a force acts on a mass. Force = Mass x Acceleration

Newton’s third law of motion

Law of action and reaction. For every action, there is an equal and opposite reaction.