8. The kind of force that acts between moving surfaces is called__________.
A. kinetic friction
B. static friction
C. rolling friction
D. sliding friction
9. it is responsible for the wear and tear of machine parts.
A. friction
B. Gravity
C. Energy
D. Resistance
10. Which is the reason why an object to slow down and stop?
A. The friction between object causes the object to slow down and eventually stop
B. The friction attached to the object in motion has no effect to its movement
C. The absence of friction makes the moving object to slow down and stop
D. The friction can't stop or slow down the moving object
Answer (1)
8. Kinetic friction is the force that acts between moving surfaces, opposing their relative motion. It occurs when an object is already moving and encounters resistance.9. Friction causes wear and tear on machine parts by:1. Generating heat2. Causing mechanical stress3. Leading to material deformation4. Resulting in surface damageFriction's effects on machines:1. Reduces efficiency2. Increases energy consumption3. Leads to part failure4. Requires frequent maintenanceGravity (B) affects machine stability, not wear.Energy (C) is the capacity to do work, not directly related to wear.Resistance (D) is a broad term; friction is a specific type of resistance.To minimize wear and tear, machines use:1. Lubrication2. Bearings3. Surface coatings4. Regular maintenance10. Friction opposes motion, causing an object to:1. Lose energy2. Reduce speed3. Eventually stopFriction's role in stopping an object:1. Converts kinetic energy into heat2. Opposes motion with equal force3. Increases stopping distance/timeExamples:1. Car brakes use friction to stop2. Bicycle brakes rely on friction3. Footwear soles grip surfaces via frictionIncorrect options:B. Friction affects motion; it doesn't have no effect.C. Absence of friction means no resistance, so objects wouldn't slow down.D. Friction can slow down and stop moving objects.
