A block of mass `m=2kg ` is pulled by a force `F=40 N` upwards through a height `h=2 m.` Find the work done on the block by the applied force `F` and its weight mg. `(g=10m//s^2)`.
A
-20
B
-10
C
-30
D
-40
Text Solution
Verified by Experts
The correct Answer is:
D
Weight, `mg=(2)(10)=20N` work done by the applied force, `W_F=Fhcos 0^@`. As the angle between force and displacement is, `0^@ ` or `W_F=(40)(2)(1)=80J` similarly, work done by its weight `W_mg=(mg)(h)cos 180^@` or `W_mg=(20)(2)(-1)=-40J`.
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