9I: ENERGY, FORCE & SIMPLE MACHINES

When an object is pulled along the ground, the force of ... between the object and the ground makes it difficult to move.

• Chemical energy

• Friction

• Kinetic energy

• Gravitational potential energy

Friction can be decreased by ...

• Using wheels

• Using rollers

• Increasing the mass

• Increasing the surface area

• Making the ground more slippery

When balanced force act on an object at rest, it ...

• Moves at a constant speed

• Slows down

• Speeds up

• Remains stationary

When balanced force act on a moving object, it ...

• Moves at a constant speed

• Slows down

• Speeds up

• Remains stationary

Unbalanced forces causes an stationary object to ...

• Move

• Stay stationary

• Change mass

• Change weight

Unbalanced forces can cause an object to ...

• Speed up

• Slow down

• Change directions

• Move at a constant speed

The difference between a forward and backwards force is called the ...

Two main categories of force are ...

• Contact force

• Non-contact force

• Balanced force

• Unbalanced force

• Resultant force

Contact forces

• Friction

• Normal force

• Tension

• Gravitational force

• Electrostatic force

Non-contact force

• Gravitational force

• Tension

• Nuclear force

• Magnetic force

• Normal force