Q.8.9.10> Acceleration, uniform & Non uniform acceleration, positive & negative acceleration

Q.8 What do you mean by Acceleration? What is its S.I.unit?
Ans.
Acceleration:- The rate of change of velocity of a body with respect to time is called acceleration.

I.e Acceleration = Change in velocity /Time taken

=> Acceleration = Final velocity – Initial velocity /Time taken

=>a = v-u /t
where,
a =acceleration of the body
v =final velocity of the body
u =initial velocity of the body &
t = time taken

The S.I.unit of acceleration is metre per second square (m/sec^2).

It is a vector quantity.

Q.9 What is uniform and non-uniform acceleration?
Ans.
Uniform Acceleration:- A body is said to have a uniform acceleration if it travels in a straight line and its velocity increases by equal amounts in equal intervals of time.
Eg.the motion of a freely falling body is uniformly accelerated.

The velocity-time graph of a body having uniformly accelerated motion is a straight line.

Non-uniform Acceleration:- A body is said to have a non-uniform acceleration if its velocity increases by unequal amounts in equal intervals of time.
Eg The speed or velocity of a car running on a crowded city road changes continuously.

The velocity-time graph of a body having uniform acceleration is a curved line.

Q.10 What is positive and negative acceleration?
Ans.
Positive Acceleration:- If the velocity of a body increases, then the body is said to have a positive acceleration.

Negative Acceleration:- If the velocity of a body decreases, then the body is said to have a negative acceleration. Negative Acceleration is also known as retardation or deceleration.