S2_Ch11.4_friction

Friction is a_________________ force.

• contact

• non-contact

The direction of friction is _____________the sliding direction.

• same as

• opposite to

Amy is trying to push the sofa to the left. Draw an arrow to show the friction acting on the sofa.

What are the methods used to reduce friction for the following cases?

e.g. Adding lubricating oil to the window frame.

• using rolling objects

• using air cushion

• using lubricants

What are the methods used to reduce friction for the following cases?

e.g. Pulling the luggage

• using rolling objects

• using air cushion

• using lubricants

What are the methods used to reduce friction for the following cases?

e.g. Speed up the jetfoil (噴射水翼船)

• using rolling objects

• using air cushion

• using lubricants

What are the methods used to reduce friction for the following cases?

e.g. Using soapy water to take off the ring

• using rolling objects

• using air cushion

• using lubricants

What are the methods used to reduce friction for the following cases?

e.g. Pushing the trolley.

• using rolling objects

• using air cushion

• using lubricants