A bus decelerating with 4m/s2 changes its speed from 60 m s-1 to a certain value in 5 s. The final speed is:
Acceleration = – 4m/s2; Initial speed, u = 60 m s-1
Time taken = 5s
Acceleration = change in velocity per unit time
v= u + at
v = 60 – 4 x 5 = 40 m/s
If the upward direction is taken as positive, what is the sign of velocity and acceleration when a body falls freely from a height?
Both velocity and acceleration are in the downward direction. Thus, they will be considered negative as they are vectors and the upward direction is positive.
A body moving along a straight line at 20m/s undergoes an acceleration of -4m/s2. After two seconds its speed will be______.
u = 20 m/s, a = -4 m/s2, t = 2 s.
v = ?
∵ v = u + at
⇒ v = 20 + (-4) (2)
⇒ v = 20 - 8 = 12 m/s
A boy throws a ball up and catches it when the ball falls back. In which part of the motion the ball is accelerating?
Choose the correct option:
The ratio of C.G.S. to M.K.S. unit of acceleration is:
M.K.S. unit of acceleration = 1 m/s2
C.G.S. unit of acceleration = 1 cm/s2
C.G.S unit of acceleration/ M,K.S unit of acceleration = 1 cm/s2 / 1 m/s2
= 1 cm / 100 cm = 1/100 =1:100
The S.I. unit of acceleration is______.
Calculating acceleration involves dividing velocity by time or we can say, dividing the meter per second by the second. i.e. [ m/s2 = (m/s) /s ]
If a moving body comes to rest, then its acceleration is______.
If a moving body comes to rest, then its acceleration is negative, as it's velocity becomes zero, therefore the acceleration is also zero.
If the velocity of a body changes uniformly from u to v in time t, the sum of average velocity and acceleration is______.
The correct option is Option D
Average velocity = (u+v)/t
Acceleration = (v-u)/t
Thus sum of average velocity and acceleration
= (u + v )/t + (v-u)/t
Acceleration is defined as the rate of change of______.
Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity.