What are the properties and types of friction, gravity, and magnetic force?

Here are the solutions to the exercise questions:

A. Darken the circle for correct option in OMR Sheet:

1. a) Friction
   • Explanation: Friction is a contact force that arises when two surfaces rub against each other. Magnetic, gravitational, and electrostatic forces are non-contact forces.
2. d) Mass
   • Explanation: Friction, air resistance, and gravity are all types of forces. Mass is a measure of the amount of matter in an object, not a force.
3. c) pressure
   • Explanation: The Pascal (Pa) is the SI unit of pressure.
4. c) is less than static friction
   • Explanation: Rolling friction is generally much smaller than static friction (the force required to start an object moving) and sliding friction.
5. d) Things have weight
   • Explanation: Friction causes objects to slow down, stop, and wear off due to rubbing. Weight is a result of gravity, not friction.

B. Fill in the blanks:

1. A frictional force acts on a moving object to the direction of motion will slow it down.
2. A ball thrown up comes down because of gravitational force.
3. Friction always opposes motion of objects.
4. Moving parts of machines are oiled to reduce friction.
5. In a magnetic force magnet is used to attract iron objects.

C. Write 'T' for True and 'F' for False statements:

1. Friction is a useful force. T
2. Friction produces heat. T
3. Friction can be increased by making the surfaces smooth. F
   • Explanation: Making surfaces smoother generally reduces friction.
4. Rolling friction is greater than sliding friction. F
   • Explanation: Rolling friction is typically less than sliding friction.
5. The force of friction always acts in the direction of motion. F
   • Explanation: The force of friction always opposes the direction of motion.