PH | MCQs

Explanation

• A pair of unlike parallel forces (forces that act in opposite directions) with different lines of force produce a couple.
• It is also known as a moment or torque.
• This is a rotational force that tends to cause rotation around a pivot point or axis.

Explanation

To find the acceleration of the sledge, we can use Newton's second law of motion: F = ma, where F is the net force acting on the sledge, m is its mass, and a is its acceleration.

First, we need to find the net force acting on the sledge. The force applied by the man is 60 N, and the force of friction is 20 N, so the net force is:

F = 60 N - 20 N = 40 N

Next, we can plug in the values to Newton's second law:

40 N = (25 kg) × a

To find the acceleration, we can divide both sides by the mass:

a = 40 N / 25 kg = 1.6 ms^-2

Therefore, the acceleration of the sledge is 1.6 ms^-2.

Explanation

Limiting frictional force (also known as static friction) is greater than:

• Rolling friction (because rolling friction is much smaller, as it only opposes the motion of an object that is already rolling)
• Sliding friction (which is another term for kinetic friction)
• Kinetic friction (which is the frictional force that acts when an object is already moving)

Explanation

• Friction is a force that opposes motion between two bodies in contact, and it arises due to the interaction between the surfaces in contact.
• The roughness of the surfaces, including microscopic imperfections and irregularities, leads to interlocking and resistance to motion.
• This resistance is what we experience as friction.

Explanation

Centrifugal force is a fictitious force that appears to act on an object moving in a circular path, causing it to move away from the center of the circle.

It is a result of the inertia of the object, which tends to keep it moving in a straight line.

Explanation

This is a statement of Newton's second law of motion, which states that the force (F) required to accelerate an object is proportional to its mass (m).

Explanation

The weight of a body is the force exerted on it by gravity.

It depends on the gravitational pull of the planet or moon it is on.

Since the gravitational pull varies from place to place (it is stronger near the surface of the Earth than on a mountain, and weaker on the Moon than on the Earth), the weight of a body also varies.

Explanation

Momentum is the quantity of motion contained in a body.

It is defined as the product of an object's mass and velocity.

Momentum is a vector quantity and is typically represented by the symbol "p".

Explanation

Distance is a scalar quantity because it only has magnitude (amount of length) but no direction.

Distance is a measure of how far apart two points are, but it doesn't have a direction.

Explanation

Time is a scalar quantity because it only has magnitude (duration) but no direction.