chapter 2

What must an accelerating object have acting on it, according to Newton's second law?

A net force.

An object moving in a circle requires a net force directed towards the center of the circle. What is this force called?

Centripetal force.

In the absence of centripetal force, what path will an object moving in a circle follow according to Newton's first law?

A straight line.

The force that acts towards the center of the circular path around which an object is moving is called c_______ f_______.

centripetal force

The apparent force that appears to act in a direction pointing away from the center of the circle is called c_______ f_______.

centrifugal force

Is centrifugal force a real force?

No, it is an apparent or fictitious force.

What causes the centrifugal force felt by passengers in a car during a sudden turn?

The effect of inertia.

When a car turns on an unbanked road, which force provides the required centripetal force?

Frictional force between the tires and the road.

Explain the purpose of banking a road.

To provide the necessary centripetal force for automobiles to take a safe turn without skidding.

The angle that the inclined track of a banked road makes with the horizontal is called the b_______ a_______.

banking angle

On a banked road, which component of the normal force provides the centripetal force?

The horizontal component.

In the case of a banked road, if the entire centripetal force is supplied by the horizontal component of the normal force, is frictional force required?

No, frictional force is not required.

The magnitude of the centripetal force acting on a body of mass m moving with speed v in a circular path of radius r is given by .

F_c = m v^2 / r

The magnitude of the centripetal force can also be expressed in terms of mass, radius, and angular velocity by the formula .

F_c = m r \omega^2

The equation showing that the horizontal component of the normal force equals the required centripetal force is .

F_N \sin \theta = m v^2 / r

The equation that relates the banking angle theta to the speed v, radius r, and gravity g is .

\tan \theta = v^2 / (rg)

A skater forming a circle must lean inwards. Explain this using a force diagram.

The frictional force between the feet and the ground provides the necessary centripetal force.

Explain the sedimentation principle in a laboratory centrifuge.

Radial acceleration causes denser particles to settle to the bottom of the tube, while low-density substances rise to the top.

A machine used to convert mechanical energy into hydraulic energy using centrifugal force is known as a c p.

centrifugal pump

How is centrifugal force used in a washing machine?

It is used to remove excess water from the clothes by spinning them very fast.

A device used to measure and regulate the speed of a machine, consisting of two balls of equal mass attached to arms, is known as a c g.

centrifugal governor

What provides the centripetal force for a satellite orbiting a planet?

The gravitational force of the planet on the satellite.

What force acts as the centripetal force when a car moves in a circular path which is inclined to the horizontal?

The horizontal component of the normal force.

What happens to the required centripetal force if the radius of curvature of an athlete's path becomes smaller?

The required centripetal force becomes greater.

If the radius of a curve is smaller and the required centripetal force is greater than the available frictional force, what happens to the moving object?

It will slip/skid.

When whirling a body attached to a string, what force originates and acts as the centripetal force?

Tension force.

What is the force that provides the required centripetal force for an electron to orbit the nucleus in an atom?

The Coulomb attractive force (Electric force).

When a plane tilts, which component of the upward thrust provides the centripetal force for a turn?

The horizontal component.

In the comparison table, which force is a real force acting towards the center?

Centripetal force.

Which force is a fictitious force acting radially away from the center due to inertia?

Centrifugal force.

Describe the centrifugal action in a washing machine.

The clothes are spun very fast and excess water is removed completely with the help of centrifugal force.

When a ball is whirled in a vertical circle, why does the tension force need to be greater than the weight at the lowest point?

To provide the required net centripetal force acting upward.

What is the limiting speed for a banked road?

The speed at which the entire centripetal force is supplied by the horizontal component of the normal force, so that frictional force is not required.

Name the two main forces encountered in circular motion mentioned in the text.

Centripetal force and centrifugal force.

What provides the centripetal force for a car making a turn on a flat, unbanked road?

The frictional force acting upon the tires of the car.

Describe the application of upward thrust (lifting force) in an aeroplane.

When the aeroplane tilts, the horizontal component of the lifting force causes the aeroplane to turn in a curve.