Science questions in short. [2 marks ]

An electrostatic force is responsible for the attraction between balloon and wall. When an inflated balloon is rubbed with a piece of synthetic cloth, it becomes charged. A charged body attracts an uncharged body. Hence, on pressing balloon against a wall, it sticks to the wall.

The two forces on the rocket immediately after leaving the launching pad are:
Gravitational Force: It is force acting on rocket pulling it in the downward direction.
Frictional force: It is the force acting due to presence of earth’s atmosphere, which opposes its motion in upward direction.

When two like charges come in close vicinity of one another then they will repel each other. There are two types of charges positive and negative charges. When two positives or two negative charges come close to one another, they repel.

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.

The force which occurs due to the action of muscles is called muscular force. To apply muscular force, there should be physical contact between both the objects. For example: when a bullock pulls a cart, its muscles apply the force on the cart. This happens only if the cart is bounded to the bullock.

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.

When we are pushing an object, our hands apply muscular force on the object which results in movement of the object. Thus it means that we are applying force on the object.

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.

The atmospheric pressure acting on our body from outside is balanced by the blood pressure acting from inside. That is why, we do not get squashed at sea level.

Yes, there will be gravitational force between the astronauts because every object in universe, whether small or large, exerts a force on every other object, it is the universal law of gravitation.

If the magnitudes of the two forces are unequal then the net force acting on the object is the difference between the two forces and the object will moves towards the direction of the larger force applied.

We are able to walk because friction acts between our feet and the ground in the opposite direction. Friction helps to get the grip without slipping. More the friction more is the grip. As the surface ice is smooth, friction is less resulting in the lesser grip. Therefore it is difficult to walk on ice.

Electrostatic force is the force exerted by one stationary object having an electric charge on other stationary object having an electric charge. If the charge on both the objects is same, they will repel and if the charge on both the objects is different then they will attract each other. There are mainly two types of charges: positive and negative.

Here the balls acquire a charge from other negatively or positively charged bodies.

The force exerted by the muscles of arms or legs or any other body part in order to do some work is called muscular force. Kicking a football, pushing a car are some examples.

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.

If we press the rubber ball placed on the table, it will get deformed. The extent of deformation depends on the force applied to the ball and the elasticity of the ball.
Moreover, the muscular force applied will impart potential energy to the ball which will rebind if force is released suddenly.

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.

Because at higher altitudes, the molecules of oxygen decreases, therefore we need to breathe faster to bring the few oxygen molecules into the lungs to make up for the deficit.

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.

Pressure is force per unit area. As the area decreases, the pressure will increase. The tip of the needle is sharp that is it has a minimum surface area than the rest of the needle. So when it is used in sewing, more pressure will be applied at the tip which helps in sewing through thick clothes.

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

The pressure inside our body is equal to the atmospheric pressure. Thus pressure inside cancels the pressure outside and preventing the head from being crushed.

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.

A bowler throws a ball with a certain force in a certain direction. As soon as the batsman hits the ball with the bat, the speed and direction of ball changes. The force applied by the batsman will determine the distance covered by the ball. If he strikes the ball with greater force then it will be a boundary and if he applies force of lesser magnitude then he may get one or two runs.

At higher altitude, the number of air molecules per unit area decreases. As a result, the force exerted by the air molecules decreases resulting in low pressure at higher altitudes.

Heavy vehicles have broad tyres because broad tyres have a large area of contact and thus exert less pressure on the ground. Because of this, heavy vehicles can move even on soft roads and fields without sinking.

Barometer is the device used to measure atmospheric pressure. It consists of a long tube containing mercury which is dipped upside down into a container of mercury. A figure is given below:

Force refers to a push or a pull that changes the state of rest or uniform motion of an object or changes the direction or shape of the object. For example: kicking a football, lifting a book.

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.

Shape of an object generally gets deformed or reformed when a force of sufficient magnitude is applied. For example: When we hit the wall with our hands, the wall will not get deformed but if we hit it with a hammer, it will break down.

Pressure exerted by the liquid depends on the depth and amount of the liquid in a tube and acceleration due to gravity.

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.

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

The two broad categories of forces are: Contact force: It is a force where physical contact between two objects is required. For example: Muscular force, friction. Non-contact force: This force does not require any physical contact between the objects. For example: gravitational force, magnetic force.

Interaction between two objects is required for a force to come into play. The interaction of one object with other results in a force between two objects but no physical contact is necessary.

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.

Camels have padded feet that imply that its feet have more area. So when they walk on the sand, their body exerts less pressure on the sand which prevents them from sinking and thus helps them to walk.

Atmospheric pressure refers to the number of air molecules per unit area. As we go to higher altitude, the number of air molecules decreases which results in a decrease in the magnitude of force exerted by them. So the atmospheric pressure will be greater at ground level.

A sharp axe has a sharp edge which means edge has a minimum area as compared to the rest of the axe. As the area is small, the pressure is large and thus easier to cut trees. Whereas blunt axe has larger edge thus exerting less pressure and hence it takes time to cut trees.

The magnitude of forces will be equal and it acts in opposite direction, so that they are cancelling each other. We can understand this by using the following diagram:

When a force is applied to an object at rest or in motion, it changes the speed and direction of motion of the object resulting in the object coming to rest or in motion in other direction with some different speed than the initial one. Therefore, a change in the speed of the object and the direction of motion of the object is referred as change in the state of the object.