The Forces Physics - The Forces

If all matters were made of electrically neutral particles such as neutrons:

1. There would be no force of friction.
2. There would be no tension in the string.
3. It would not be possible to sit on a chair.
4. The earth could not move around the sun.

Action and reaction:

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

When Neils Bohr shook hand with Werner Heisenberg, what kind of force they exerted?

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

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.

A proton exerts a force on a proton which is:

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

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).

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

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?

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

A boy is sitting on a chair placed on the floor of a room. Write as many action-reaction pairs of forces as you can.

Figure shows a boy pulling a wagon on a road. List as many forces as you can which are relevant with this figure. Find the pairs of forces connected by Newton's third law of motion.

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?

A lawyer alleges in court that the police has forced his client to issue a statement of confession. What kind of force is this?

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

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?

The geostationary orbit of the earth is at a distance of about 36000km from the earth's surface. Find the weight of a 120kg equipment placed in a geostationary satellite. The radius of the earth is 6400km.

Calculate the force with which you attract the earth.

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.

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.)