11.3 Physical Science Forces, Energy, and Motion

Reading Motion and Force Like a GED Scientist

Physical science on the GED often looks mathematical, but the test is not trying to make you memorize a formula sheet. GED prompts usually provide the formulas or enough information to reason from the relationship. Your job is to decide what the quantities mean, use consistent units, and check whether the result makes sense.

Motion From Tables and Graphs

Speed is distance divided by time. Velocity includes direction. Acceleration is a change in velocity over time. A distance-time graph with a steeper slope shows a faster object. A flat line means the distance from the starting point is not changing.

Cart A travels 12 meters in 6 seconds, so its average speed is 2 meters per second. Cart B travels 9 meters in 6 seconds, so its average speed is 1.5 meters per second. Because both distances increase by the same amount every 2 seconds, each cart is moving at a constant speed in this data set.

Force, Mass, and Acceleration

Newton's laws explain common GED scenarios. An object at rest tends to stay at rest unless acted on by a net force. A greater net force can produce greater acceleration. A greater mass is harder to accelerate with the same force. Forces also occur in pairs: when one object pushes another, the second object pushes back with equal strength in the opposite direction.

Use this experimental data for carts pushed with different forces.

The table shows two relationships. When mass stays at 2 kg and force doubles from 4 N to 8 N, acceleration doubles. When force stays at 8 N and mass doubles from 2 kg to 4 kg, acceleration is cut in half. This is the pattern behind F = m x a.

Work, Power, and Simple Machines

Work happens when a force moves an object through a distance. Power is how quickly work is done. Simple machines, such as ramps, pulleys, levers, and wheels, can make work feel easier by reducing the force needed, but the tradeoff is usually moving the object over a longer distance.

A ramp does not remove the need for energy. It spreads the effort out. On the GED, if a ramp lets a worker use less force to lift a box, expect the distance along the ramp to be longer than the straight vertical lift.

Energy and Waves

Energy changes form: chemical energy in food becomes motion and heat; electrical energy in a lamp becomes light and heat; gravitational potential energy in a raised object becomes kinetic energy as it falls. The total energy is conserved in a closed system, but useful energy can spread out as heat.

Waves transfer energy. GED questions may ask about wavelength, frequency, amplitude, or electromagnetic radiation. A higher-frequency electromagnetic wave carries more energy than a lower-frequency one, which helps explain why ultraviolet light can damage skin while radio waves are used for communication.

For any physical science data set, read the headings and units first. Then compare one variable at a time. GED questions reward the conclusion that matches the measured pattern.