alleryStart learning →A block sits still on a bench while nobody pushes it. What is the friction on it?
AKinetic friction at full value
BStatic friction, and it is zero
CKinetic friction pointing upward
DStatic friction at its maximum
Answer & Solution
Correct answer: B. Static friction, and it is zero
1. Static friction is the type that acts when surfaces are not sliding.
2. It is a responding force, taking whatever value is needed to balance the push applied.
3. With no push applied there is nothing to balance, so the friction is zero.
4. Its maximum value only matters at the instant the block is about to slip.
_Source: OpenStax College Physics (CC BY 4.0), Ch 5 "Further Applications of Newton's Laws: Friction, Drag, and Elasticity", section Kinetic Friction_
Keep practising Friction, Drag, and Elasticity
Browse all Friction, Drag, and Elasticity questions for UAE MoE Grade 12, or explore more Physics topics.
Related questions
What happens to the downward force of gravity on a skydiver as their speed rises?Which two forces act on a skydiver falling through air, once buoyancy is ignored?What would a nearly friction-free environment save on a large scale?What kind of characteristics of friction are the simple rules taught at school?Which of these is the standard everyday example of kinetic friction acting?Why do two surfaces become warm when they are rubbed together?Adding a heavy box on top of a crate makes it harder to push. Why?Oiling a concrete floor makes a crate easier to move. What has changed?