The instantaneous velocity of a 2kg body is given by-
v=18t + 3 where v=instantaneous velocity(in m/s) and t=time(in seconds)
Find the work done by the force from t=0sec to t=5sec.(in Joules)
My inspiration Aniket Sanghi
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Sir, how to make Integration sign bigger?
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Nice and concise. I knew that the force is not variable, so I did not use any calculus, because I did not incorporate power into my solution. Good solution.
Since the force is constant, the definition of work as an integral is not needed. The acceleration is found by
d t d v , which in this case is 18m/s 2
Newton's second law:
F = m a = 2 ∗ 1 8 = 3 6 N
Work:
W = F d = 3 6 d
displacement is found by integrating velocity:
∫ 1 8 t + 3 = 3 t + 9 t 2
substituting t=5;
d = 2 4 0
Therefore, the work done is 3 6 d = 2 4 0 ∗ 3 6 = 8 6 4 0 J
Displacement:
s = ∫ 0 5 v d t = ∫ 0 5 ( 1 8 t + 3 ) d t = 2 4 0
Acceleration:
a= d t d v
= d t d (18t+3)
=18m/s 2
Energy
E=Fs
=mas
=2×18×240
=8640
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Power:
P = F v = m a v = 2 ( 1 8 ) ( 1 8 t + 3 ) = 3 6 ( 1 8 t + 3 )
Energy:
E = ∫ 0 5 P d t = 3 6 ∫ 0 5 ( 1 8 t + 3 ) d t = 3 6 ( 9 ( 5 2 ) + 3 ( 5 ) ) = 8 6 4 0