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Fourth Grade Science

Forces Study Guide

Fourth Grade

Motion – a change in position.

Position – the location of an object.

Distance – how far apart two points or places are.

Speed – a change in distance over time; how fast an object is moving. Speed = distance divided by time.

Velocity – an object’s speed AND direction of motion.

Force – a push or pull.

Acceleration – any change over time in the speed or direction of a moving object.

Greater force gives an object more acceleration.

Inertia – the tendency of an object in motion to stay in motion, or an object at rest to stay at rest.

The more mass an object has, the more inertia it has.

Friction – a force that works between the surfaces of objects that touch and cause the object to slow down or completely stop.

Gravity – a force that acts over a distance and pulls all objects together.

The pull of gravity depends on the amount of matter and the distance between the objects.

Balanced forces – forces that cancel each other out when acting together on a single object. Each force is equal in size and opposite in direction. Does not cause a change in motion. When an object is still, the forces acting are balanced.

Unbalanced forces – forces that are not equal to each other. Cause a change in motion toward the greater force.

Newton – unit used to measure force; named after Isaac Newton.

Work – when a force is used to move an object a certain distance.

Energy – the ability to do work.

Potential energy – stored energy. Potential energy can change to kinetic energy easily -> when the object begins to move.

Kinetic energy – energy of motion.

Forms of energy:

  • Chemical Energy – energy your body uses that is stored in food.
  • Electrical Energy – energy related to the movement of charged particles that comes from batteries or power plants.
  • Light Energy – energy that comes from the Sun.
  • Mechanical Energy – energy that is the sum of kinetic and potential energy.
  • Thermal Energy – energy that comes from heat.
  • Nuclear Energy – energy that comes from the tiniest particles of matter.

Energy is transformed when it changes from one form to another.

Energy is transferred when it passes from one object to another.

Produce energy – the conversion of stored energy into a desired form for practical use.

Machine – anything that helps us do work.

Simple machine – a machine with only a few parts.

Lever – a simple machine with a straight bar that moves on a fixed point and can be used to lift objects. Example: see-saw, crow bar.

Load – the object being moved by a lever.

Effort force – the force used to do work.

Wheel and Axle – a lever made up of a wheel that moves around a post. Example: Ferris wheel, door knob.

Pulley – a lever that uses a rope and a wheel to lift an object.

Inclined plane – a simple machine with a flat, slanted surface. Example: ramp.

Wedge – a simple machine that splits objects apart. Example: knife, axe.

Screw – an inclined plane wrapped into a spiral. Example: screw, top of a water bottle.

Compound machine – two or more simple machines put together.

Efficiency – how much work a machine produces compared to the amount of work applied.

**Students should have numerous diagrams, foldables, and notes in their science notebooks that will provide all of the resources necessary to prepare for this test.