Explanation
A ball is thrown upwards. It takes 4 s to reach back to the ground. Find its initial velocity.
A boy standing at the top of a tower of 20 m height drops a stone. Assuming g=10ms−2, the velocity with which it hits the ground is:
The velocity of a bullet is reduced from 100 m/s to 0 m/s while travelling through a wooden block of thickness 10 cm. The retardation, assuming it to be uniform will be:
A ball is dropped from height h and another from 2h. The ratio of time taken by the two balls to reach ground is:
If a body is thrown up with the velocity of 15m/s, then maximum height attained by the body is (g=10 m/s2)
Hint:
The slope of the curve in a velocity – time graph gives the acceleration.
Step1:Slope of velocity-time graph
Slope of velocity – time graph gives acceleration as shown below:
slope=ΔvΔt=a
Step2:Conclusion from graph
According to the graph of the question, the initial velocity of the body at time t=0 is OA. The slope of the graph is constant but negative.
Acceleration is a vector quantity having both magnitude and direction. Increase in velocity with respect to time is called acceleration whereas decrease in velocity with respect to time is called retardation. In this graph, the velocity is decreasing at a constant rate with respect to time. Hence, the body shows uniform retardation.
The correct answer is option (D).
velocity=Change in displacementtime
Hence, The rate of change of displacement with time is velocity
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