Laws Of Motion Question 129

Question: A 15 kg block is initially moving along a smooth horizontal surface with a speed of v=4m/s to the left. It is acted by a force F , which varies in the manner shown. Determine the velocity of the block at t=15 seconds. Given that, F=40cos(π10)t

Options:

A) 12.5 m/s

B) 8.5 m/s

C) 20 m/s

D) 9.5 m/s

Show Answer

Answer:

Correct Answer: A

Solution:

[a] Change in liner momentum ΔP=Fdt

15(vf+u)=01540cos(π10)tdt

vf=4+4015[sin(π/10)tπ/10]150=4+40015π(1)

=12.5m/s



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