Unit13: Forces

Which of the following statements best describes balanced forces?

• Forces that change the motion of objects

• Forces that stop a moving body

• Forces that are equal in strength and opposite in direction

• Forces that increase the speed of a moving body

What effect can forces have on a moving body?

a) Stop a moving body

b) Change the direction of a moving body

c) Change the mass of the body

• a) only

• b) only

• c) only

• a) and b)

• a), b) and c)

Which of the following represents the strength of a force?

• Direction

• Magnitude

• Interaction

• Friction

Which type of force requires physical contact between two bodies?

• Balanced forces

• Unbalanced forces

• Contact forces

• Non-contact forces

When unequal forces act on a body, either in the same direction or opposite directions, it is called:

• Balanced forces

• Friction

• Unbalanced forces

• Air resistance

Friction is a force that is created when:

• Two surfaces are in contact with each other

• Two surfaces are not in contact with each other

• A body falls towards Earth

• Air resistance is experienced

How can friction be increased?

a) By making surfaces rough

b) By using lubricants

c) By attaching wheels or rollers

• a) only

• b) only

• c) only

• a), b) and c)

• b) and c)

How can air resistance be reduced?

• By making surfaces rough

• By using lubricants

• By attaching wheels or rollers

• By making the body streamlined

The force of friction is always in the direction:

• Perpendicular to the direction of motion

• Parallel to the direction of motion

• In the direction of motion

• Opposite to the direction of motion

The amount of air resistance also depends upon the:

a) Shape and size of the body

b) Speed of the body

c) Mass of the body

• a) only

• b) only

• c) only

• a) and b)

• a), b) and c)