Consider two frames of reference S and S', the first one being fixed to the ground and the second one fixed to a moving train moving with 5.00m/s with respect to the ground (figure). A block of mass 4.00kg, initially at rest with respect to S', is acted upon by a 14.0N force for 3.00 in the positive x direction. Neglect friction.

According to an observer in S', what are the corresponding quantities?

Options

A. the initial kinetic energy of the block is zero
B. final kinetic energy 220.5J
C. the change in kinetic energy 220.5J
D. the work done by the force on the block is 220.5J

Explanation

`v=0+(7)/(2)xx3=(21)/(2)`
`k_(r)=(1)/(2)xx4xx(21xx21)/(4)=(441)/(2)=220.5J`
`s=0+(1)/(2)xx(7)/(2)xx9=(63)/(4)`
`w=14xx(63)/(4)=(441)/(2)=220.5J`