Force And Pressure Flashcards
Give two examples, each are situations in which you push or pull to change the state of motion of objects.
Example for push:
moving a loaded car
a cricket ball hit by a batsman.
Example for pull:
opening a door
moving a chair towards you.
Give two examples of situations in which applied forces cause a change in the shape of an object.
- Stretching of a rubber band.
- Making chapati from a ball of dough.
A blacksmith hammers a hard piece of iron while making a tool. How does the force due to hammering affect the piece of iron?
The force of hammering changes the shape of iron in the form of the desired tool.
Name the forces acting on a plastic bucket containing water held above ground level in your hand. Discuss why the forces acting on the bucket do not bring a change in its state of motion.
Gravitational forces act on the plastic bucket containing water held above ground level in our hand. We know that gravitational forces do not bring a change in its state of motion because an equal amount of force is being applied vertically upwards.
A rocket has been fired upwards to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after hearing the launching fire.
The two forces acting on the rocket are force due to gravity acting vertically downwards, and frictional force of atmosphere.
What is force? List the effects of force.
A simple push or pull exerted by an object on another is called force. The following are the effects of force:
- Change in shape of the object.
- Change in direction of motion of an object.
- Change in speed of an object if it is moving.
- Movement of an object from rest.
Some or all of the above effects can be seen.
Explain the different types of forces.
Forces can be mainly classified into contact forces and non-contact forces.
Contact force:
A force that can be applied only when it is in contact with an object is called contact force. It includes muscular force and frictional force.
Muscular force:
The force resulting due to the action of muscles is known as muscular force.
Example: writing, cutting vegetables.
Frictional force:
The force that opposes the state of motion of objects is called frictional force. It always acts on a moving object, and its direction is always opposite to the direction of motion.
Example: stopping of a ball rolling on the ground due to friction.
Non-contact force:
A force that can be applied without any contact between two objects is called non-contact force. It includes gravitational force, magnetic force, and electrostatic force.
Gravitational force:
The force exerted by the earth to pull the object towards itself is called the force of gravity.
Example: a ball projected outwards falls back on earth.
Magnetic force:
A force exerted by a magnet to pull or push a metallic object is called magnetic force.
Example: the force exerted by a magnet on iron.
Electrostatic force:
When a charged body, whether positive or negative, exerts force on another uncharged or charged body, that force is known as electrostatic force.
Example: sticking of an inflated balloon to the wall after rubbing it with a dry cloth.
What is pressure? Write the unit of pressure.
The force acting on a unit area of surface is called pressure. To find pressure, we need to divide force by the surface area on which it acts.
Pressure equals force by area.
Newton per meter square (N/m²) is the unit of pressure.
On what factors does the effect of force depend?
It depends on:
1. The amount of force applied: The more the applied force, the greater will be the effect.
- The area on which the force is applied: The smaller the area the force is applied on, the greater will be the effect.
What is atmospheric pressure?
The pressure exerted by the atmospheric air on the surface or by the weight of air above that surface is known as atmospheric pressure.
Explain the significance or uses of atmospheric pressure.
Atmospheric pressure is necessary as it takes place in various aspects of human life. Some uses of atmospheric pressure include:
- Vacuum cleaners use atmospheric pressure to suck in the dust.
- Filling ink uses atmospheric pressure to suck in the ink.
- Vacuum suckers used in toys to stick to a certain surface.
