Friction

The image shows a person rowing a boat over a river.

Identify the number of bodies experiencing friction

•      1, boat because of the river.

• 1, boat because of the person

• 2, boat because of the river and the person because of the air

• 2, boat because of air and river and the person because of air

Which of the following is an example of drag?

• A book resting on a table.

• Air resistance acting on a falling parachute.

• A person sliding down a slope.

• Friction between a car's tires and the road.

How can drag be reduced for objects moving in a fluid?

• Increasing the speed of motion.

• Using streamlined shapes.

• Roughening the surface of the object.

• Increasing the weight of the object.

Which of the following increases friction?

• Applying oil to a surface.

• Using sandpaper on a surface.

• Polishing a surface.

• Using ball bearings.

Why is friction called a necessary evil?

• It can only harm objects.

• It always opposes motion.

• It is both beneficial and disadvantageous.

• It reduces the efficiency of machines.

In which situation is friction essential?

• Heat generation in machine parts.

• A person walking without slipping.

• The wearing out of shoes.

• Energy overuse

What happens when friction is reduced too much in some cases, such as icy roads?

• Movement becomes impossible.

• Objects move faster than expected.

• Objects lose control and stability.

• Friction increases automatically.

Which of the following demonstrates reducing friction?

• Adding grooves to tires.

• Wearing shoes with better grip.

• Using oil in a car engine.

• Applying brakes to a vehicle.

Which type of friction is at work when a person tries to push a stationary heavy box?

• Rolling friction

• Static friction

• Sliding friction

• Fluid friction

Why do athletes use spikes in their shoes?

• To decrease friction.

• To increase rolling friction.

• To increase grip by increasing friction.

• To reduce drag while running.