Science Question Answer (2 Marks)

20m below the surface of sea.
Pressure increases with height or depth of sea level.

The force of attraction between all masses in the universe, especially the attraction of the earth's mass for bodies near its surface. For example: When you hold a ball up in the air, the mass of Earth allows the ball to fall to the Earth.

Non-Contact Forces are the forces exerted by an object that can be experienced by an object even from a distance without any contact with each other Magnetic, Electrostatic and Gravitational Forces are Non-Contact Forces.

1. Contact Forces (Frictional Force, Tension Force, Normal Force, Air Resistance Force, Applied Force and Spring Force).
2. Action-at-a-Distance Forces (Magnetic Force, Electrical Force, Gravitational Force).

When we filled air in the balloon, the inside pressure in the balloon increases and thereby the surface area of balloon increases. Thus the force acting by air molecule inside outward and the force acting by air from outside inward equals. This balancing force tend to make a balloon get inflated when air is filled in it.

When a man stands on a cushion then only his two feet (having small area) are in contact with the cushion. Due to this the weight of man falls on a small area of the cushion producing a large pressure. This large pressure causes a big depression in the cushion.

1. Drinking Straw works on atmospheric pressure.
2. Vacuum Cleaner works on atmospheric pressure.

The two hemispheres pressed together when vacuum is created between them because air is pumped out of the interior which create the remarkable force between them to stick together.

1. Drinking Straw.
2. Vacuum Cleaner.

1. Gravitational force.
2. Magnetic force.

The force acting on an object without being in contact with it is known as non contact force.

The snow shoes have large, flat soles so they exert less pressure (= force/ area) on the soft snow and stop the wearer from sinking into it.

Muscular force is a force which is generated by our muscles during heavy works, exercises etc which produce lactic acid. The example of muscular force is bouncing a ball.

Electrostatic force.
The force acting on object due to its charged.

Magnetic forces are the force due to magnetic field of a magnet. The closing of door of refrigerator works on the application of magnetic forces.

Same magnitude of force are acting in opposite direction. Therefore they cancel each other.

1. Frictional force.
2. Applied force.

The force applied when it is in a contact with the object.

Lesser the area, larger the pressure for the same force applied. Therefore it is easier to cut with sharp knives than blunt ones, with same force.

Electrostatic force.
On the rubbing an object to get charged (static charge) and unlike charges get attracted to each other, such type of force is Electrostatic force.

As we know that air and water are the matter and matter has a characteristic property which says that they have mass and occupy certain space. So when air or water is filled in balloon, they tend to stretch its rubber boundary and occupy the space. Therefore, the shape and size of balloon get change when filled with air or water.

The tip of sewing needle is sharp because with decrease of area, pressure increases and the needle can easily penetrate the stitching material.

1. Pushing a carom board coin.
2. Moving a glass placed on table.

The force can change the state of motion on applying on it.

At higher altitude the atmospheric pressure decreases therefore the blood vessels exceed the outside pressure which causes blood vessels to get rupture.

The state of motion of an object is define by the speed acquired by it in a particular direction. Force can change the state of motion of an object.

Upward muscular force applied by hand and downward gravitational force applied by earth; The two forces being equal and opposite balance each other and hence do not bring a change in the state of motion.