What are Forces?

What does a contact force require?

• The objects to not be touching

• The objects must be touching

• The objects can be touching or not touching

Answer explanation

For a contact force to act, the objects must be touching

Which of these is true of non contact-forces?

• The objects to not be touching

• The objects must be touching

• The objects can be touching or not touching

Answer explanation

The objects could be touching like when weight is exerted on you on the Earth, or could not be touching like when gravity from the Earth acts on the moon.

Which of these is a contact force?

• Gravity

• Magnetic

• Friction

• Electrostatic

Answer explanation

Friction is the contact force.

Which of these is exerted by an engine?

• Thrust

• Water resistance

• Friction

• Air resistance

Answer explanation

Thrust is the force exerted by an engine.

Which of these is in the same direction as the movement of the object?

• Thrust

• Water resistance

• Friction

• Air resistance

Answer explanation

Thrust is in the same direction as the movement of the object.

Which unit do we measure force in ?

• Newton (N)

• metre (m)

• Joules (J)

• kilogram (kg)

Answer explanation

Force is measured in Newtons. This is the unit of force.

Which four forces act on a plane?

• Air resistance, Water resistance, Weight and Thrust

• Air resistance, Upthrust, Weight and Thrust

• Water resistance, Lift, Weight and Upthrust

• Air resistance, Lift, Weight and Thrust

Answer explanation

Air resistance, Lift, Weight and Thrust all act on a plane while it is flying.

Which force causes boats to float?

• Thrust

• Upthrust

• Lift

• Water resistance

Answer explanation

The other forces might also act on the boat, but the upthrust is the one that keeps it from sinking.