Fluid Friction

Q. Imagine that an object is falling through a long straight glass tube held vertical; air has been removed completely from the tube. The object does not touch the walls of the tube. Will the object experience any force of friction?
[2 marks]
[Exemplar]
[Fluid friction]

Q. It is because of air drag that cats don't get hurt on falling from a height.

1. True
2. False

Q.

What is the frictional force exerted by fluids on objects moving through them known as?

1. Lift

2. Thrust

3. Drag

4. Weight

Q.

An aeroplane flying in the atmosphere experiences no friction.

1. True

2. False

Q. The frictional force on any object exerted by fluids are called _________

1. normal force
2. magnetic force
3. drag force
4. electrostatic force

Q. Birds fly through the air. What force(s) act on the birds?

1. Sliding friction
2. Air drag
3. Gravitational force
4. Static friction

Q. A space shuttle while descending rapidly to the surface of earth from a mission gets heated up intensely and catches fire. Assuming no malfunctioning of its engine or components, what can be a possible cause?

1. Gravitational pull of the Sun is too strong on the shuttle.
2. Earth's atmosphere offers frictional force.
3. Velocity of the shuttle is too low.
4. Parachutes are attached.

Q. How does a cat not hurt itself on jumping or falling from a height?

1. It has soft skin which prevents injury.
2. It brings its legs close together such that its weight is evenly distributed when it lands.
3. It uses its tail to save itself.
4. It spreads its legs wide apart and increases air drag.

Q. A footballer throws a ball in the air. In air what type of friction is acting on the ball?

1. Sliding friction
2. Rolling friction
3. Static friction
4. Air drag

Q.

Which of the following methods will help in reducing air drag?

1. Using ball bearings

2. Polishing

3. Using lubricants

4. Streamlining