Define acceleration and state its SI
unit. For motion along a straight line,
when do we
consider the acceleration to be (i)
positive (ii) negative? Give an
example of a body in uniform
acceleration.
Answers
acceleration:-rate of change of velocity
formula:- a=v-u/t
SI unit=m/s^2
position acceleration:-when a body's acceleration increases it us said to be positive acceleration
ex:-acceleration increases from 20m/s^2 to 25m/s^2
negative acceleration:-when acceleration decreases. also called 'deceleration'
ex:-acceleration decreases from 25m/s^2 to 20m/s^2
Uniform acceleration:-when a body's acceleration is constant
ex:-a body's acceleration is 5 at 1st second,10 at 2nd second, 15 at 3rf second like that
Acceleration is the rate of change of velocity with time.
→Explaination
→During uniform motion of an object along a straight line,the velocity remains constant with time.In this case ,the change in velocity of an object for any time interval is zero.
→Hence the acceleration will also be 0.
However,in non-uniform motion,velocity varies with time.It has different values at different instats and at different points of the path.Thus , the change in velocity of the object during any time interval is not zero.
→Hence acceleration will not be equal to 0.
→acceleration=change in velocity/time
a=(v-u)/t
SI unit of acceleration=m/s²
when the velocity of a body increases with time then it is said to be positive acceleration
when the velocity of a body decreases with time then it is said to be negative acceleration
Extra info
three related to uniform acceleration
- v=u+at
- v=u+ats=ut+1/2at²
- v=u+ats=ut+1/2at²v²=u²+2as