Science
A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 ms-2, with what velocity will it strike the ground? After what time will it strike the ground?
Motion in One Dimension
1 Like
Answer
Given,
Initial velocity (u) = 0
Distance travelled (s) = 20 m
Acceleration (a) = 10 ms-2
As per the third law of motion,
v2 – u2 = 2as
Substituting we get,
v2 - 0 = 2 x 10 x 20
⇒ v2 = 400
⇒ v =
⇒ v = 20 ms-1
Hence, ball strikes the ground with a velocity of 20 ms-1
As per the first equation of motion,
v = u + at
or
t =
Substituting we get,
t = = 2 seconds
∴ the ball reaches the ground after 2 seconds.
Answered By
1 Like
Related Questions
A driver of a car travelling at 52 kmh-1 applies the brakes. Shade the area on the graph that represents the distance travelled by the car during the period.
(b) Which part of the graph represents uniform motion of the car?
Fig below shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:
(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d) How far has B travelled by the time it passes C?
The speed-time graph for a car is shown in Fig. below
(a) Find how far does the car travel in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period.
(b) Which part of the graph represents uniform motion of the car?
State which of the following situations are possible and give an example for each of these:
(a) an object with a constant acceleration but with zero velocity
(b) an object moving with an acceleration but with uniform speed.
(c) an object moving in a certain direction with an acceleration in the perpendicular direction.