Engineering Mechanics

- Statement (A) is false as frictional force is not directly dependent on the area of contact, but rather on the nature of the surfaces in contact and the normal force.
- Statement (B) is true since frictional force always acts in the tangential direction to the surface in contact.
- Statement (C) is true because the maximum value of static friction is known as limiting friction.
- Statement (D) is true as dynamic friction is also referred to as kinetic friction, which occurs when the surfaces are in relative motion.

Forces whose lines of action pass through a common point are called concurrent forces These forces can act at the same point but in different directions.

The time for the upward and downward journey is the same in the absence of air resistance as gravity acts equally on both the upward and downward journeys Since the time taken for the upward journey is 10 seconds the downward journey will also take 10 seconds Therefore the total time for the entire journey is 10 + 10 = 20 seconds