A 10 kg box initially at rest is pulled with a 50 N horizontal force for 4 m across a level surface. The force of friction acting on the box is a constant 20 N. How much initial kinetic energy does the box
have?

A. 0J
B.10J
C.50J
D.100J

if you already have the answer to (a), then just work out how many periods there are in 1 minute, and that's the answer to (c).

wire in brush may conduct electricity from cell to drill and vice versa electrc shock possible

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s