The Forces Physics - The Forces

The sum of all electromagnetic forces between different particles of a system of charged particles is zero:

1. Only if all the particles are positively charged.
2. Only if all the particles are negatively charged.
3. Only if half the particles are positively charged and half are negatively charged.
4. Irrespective of the signs of the charges.

The two ends of a spring are displaced along the length of the spring. All displacement have equal magnitudes. In which case or cases the tension or compression in the spring will have a maximum magnitude?

1. The right end is displaced towards right and the left end towards left.
2. Both ends are displaced towards right.
3. Both ends are displaced towards left.
4. The right end is displaced towards left and the left end towards right.

Action and reaction:

1. Act on two different objects.
2. Have equal magnitude.
3. Have opposite directions.
4. Have resultant zero.

A proton exerts a force on a proton which is:

1. Gravitational.
2. Electromagnetic.
3. Nuclear.
4. Weak.

Which of the following systems may be adequately described by classical physics?

1. Motion of a cricket ball.
2. Motion of a dust particle.
3. A hydrogen atom.
4. A neutron changing to a proton.

Suppose the magnitude of Nuclear force between two protons varies with the distance between them as shown in figure. Estimate the ratio "Nuclear force/Coulomb force" for:

1. x = 8fm
2. x = 4fm
3. x = 2fm
4. x = 1fm (1fm = 10^-15m).

Is it true that the reaction of a gravitational force is always gravitational, of an electromagnetic force is always electromagnetic and so on?

Find the ratio of the magnitude of the electric force to the gravitational force acting between two protons.

A body of mass m is placed on a table. The earth is pulling the body with a force mg. Taking this force to be the action what is the reaction?

List all the forces acting on the block B in figure.

List all the forces acting on:

1. The pulley A.
2. The boy and.
3. The block C in figure.

At what distance should two charges, each equal to 1C, be placed so that the force between them equals your weight?

When you hold a pen and write on your notebook, what kind of force is exerted by you on the pen? By the pen on the notebook? By you on the notebook?

The gravitational force acting on a particle of 1g due to a similar particle is equal to 6.67 × 10^-17N. Calculate the separation between the particles.

The average separation between the proton and the electron in a hydrogen atom in ground state is 5.3 × 10^-11 m.

1. Calculate the Coulomb force between them at this separation.
2. When the atom goes into its first excited state the average separation between the proton and the electron increases to four times its value in the ground state.What is the Coulomb force in this state?

Figure shows a cart. Complete the table shown.

Calculate the force with which you attract the earth.

A satellite is projected vertically upwards from an earth station. At what height above the earth's surface will the force on the satellite due to the earth be reduced to half its value at the earth station? (Radius of the earth is 6400km.)

Two charged particles placed at a separation of 20cm exert 20N of Coulomb force on each other. What will be the force if the separation is increased to 25cm?

Two spherical bodies, each of mass 50kg, are placed at a separation of 20cm. Equal charges are placed on the bodies and it is found that the force of Coulomb repulsion equals the gravitational attraction in magnitude. Find the magnitude of the charge placed on either body.