A crate is pulled 6m along a straight floor by a constant force of 40N. For the first 4m the force makes an angle of 60∘ with the direction of motion. Without changing its magnitude, the angle is reduced to 30∘ for the remaining 2m. Calculate the total work done by the force on the crate.
a) 1.6×102J
b) 1.5×102J
c) 1.8×102J
d) 1.2×102J