Friction 2 worksheet

The difference between dry friction and fluid friction is:

• Dry friction occurs between touching surfaces, while fluid friction occurs when one object is inside another.

• Dry friction is always greater than fluid friction.

• Fluid friction is independent of the velocity of the moving object.

• Dry friction only occurs when there are 3 objects.

The space shuttle gets so hot when it reenters our atmosphere because:

• it speeds up as it descends, causing friction with the air.

• it slows down, causing heat to build up.

• it is heated by the sun's rays.

• it is powered by its engines during reentry.

Dry or surface friction depends on:

• the nature of the surfaces in contact

• the area of contact

• the speed of movement

• the temperature of the surfaces

Fluid friction depends on:

• the shape of the object

• the weight of the object

• mu

• all of the above

Fluid friction occurs because:

• fluid particles must be pushed out of the way before something moves

• fluids are weightless

• everything is attracted to the center of mass

• positive and negative parts of atoms atract

Bernoulli’s Principle states that:

• the pressure of a fluid decreases as its velocity increases

• the pressure of a fluid increases as its velocity increases

• the pressure of a fluid remains constant regardless of its velocity

• the pressure of a fluid is independent of its velocity

The shape of an airplane wing helps it to fly by creating a difference in air pressure above and below the wing, resulting in lift.

• By creating a difference in air pressure above and below the wing, resulting in lift.

• By increasing the weight of the airplane.

• By reducing the speed of the airplane.

• By making the airplane more aerodynamic.

When a ball is thrown from a quarterback to a wide reciever, when is the ball going the fastest

• as it leaves the hand

• half way in the throw

• right before the catch

• they are all about the same

Which takes more force: moving a 10 kg box (u = 0.2), moving a 30 kg box (u = 0.1), or moving a 20 kg box (u = 0.0)?

• 10 kg box (u = 0.2)

• 30 kg box (u = 0.1)

• 20 kg box (u = 0.0)

• all the same

Which of the following is an example of fluid friction?

• A fish swimming in water

• A book sliding on a table

• A car tire on a dry road

• A person walking on sand