(a) Define force and its various types. What is its unit ?
(b) What do you mean by conservation of momentum ?
(c) What change will a force bring in a body ?
(d) Why do passengers tend to fall back when it starts suddenly ?
Answers
Answer:
Force is defined as the push or pull exerted on an object which produces acceleration in ann object. Newton is the SI unit of force. Following are the three changes that can be observed on a body when force is applied:
Change in the direction of motion of the body
Change in the speed of the body
Change in the shape of the body
Force can be either balanced or unbalanced. Force is said to be balanced when they cancel out each other such that the resultant force is zero. When the force acting on a body moves the body in the direction of force which is greater than the other, it is known as unbalanced force.
Laws of motion
There are three laws of motion and they are:
First law of motion: According to the first law of motion, an object remains to be in a state of rest or in a state of uniform motion unless acted upon by a force. This law is also known as the law of inertia.
Second law of motion: According to the second law of motion, the change in momentum of an object is proportional to the applied force and is in the same direction as the force.
Third law of motion: According to the third law of motion, there is an equal and opposite reaction for every action and they act on two different objects
Answer:
( a ) It is a push or a pull acting on a body.
There are various types of forces like electrostatic force,magnetic force,gravitational force etc.
It's si unit is Newton(N)
(b) Conservation of momentum, general law of physics according to which the quantity called momentum that characterizes motion never changes in an isolated collection of objects; that is, the total momentum of a system remains constant.
(c) Force can bring the following changes: It can stop a moving body, move a stationery body, change shape of the body, alter the speed of the body, change the direction of motion of the body.
(d) When a bus starts suddenly,the person falls backwards because of inertia of rest of passenger. This is due to the fact that because of their inertia ,the passengers tend to remain in their state of rest when the bus starts suddenly.