Starting from rest a 10 kg object is acted upon by only one force as indicated in figure. Then the total work done by the force in 5 seconds is

Options

A. 90 J
B. 320 J
C. 245 J
D. 490 J

Answer

B

Explanation

Change in velocity `=("area under F-T graph")/("mass")`
`=(120+(-40))/(10)=8 m//s`
`W_(f)=DeltaK.E = (1)/(2)(10)8_(2) = 320 J`