Josie and Charlotte push a 12-kg bag of playground sand for a sandbox on a frictionless, horizontal, wet polyvinyl surface with a constant, horizontal force for a distance of 5 m, starting from rest. If the final speed of the sand bag is 0.3 m/s, what is the magnitude of the force with which they pushed?
2006-10-05 12:38:37 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
11.5 m^2/s.
2006-10-05 12:45:52 · answer #1 · answered by stevewbcanada 6 · 0⤊ 0⤋
The formula is f = m*a. With a constant force, a is constant, so the final speed of the sandbag is vf = a * t; or a = vf/t. The distånçe something moves under constant acceleration is s = .5*a*(t^2), so t =sqrt(2*s/a). Put this t into the previous eq to get a = vf/(sqrt(2*s/a)); a^2 =(vf^2)*a / (2*s) or a = (vf^2)/(2*s)
The force is then m*(vf^2)/(2*s)
2006-10-05 19:53:23 · answer #2 · answered by gp4rts 7 · 0⤊ 0⤋