I need help with these! Please show work, explanations, and equations that are u
ID: 1448734 • Letter: I
Question
I need help with these! Please show work, explanations, and equations that are used. Thanks!
2. A person lifts a 3 kg mass at a constant speed, doing a total of 15 Jof work on the mass. Which statement best describes the change in the potential energy of the mass? a) The potential energy of the mass increases by 15 J. b) The potential energy of the mass decreases by 15 J c) The potential energy of the mass increases by 5 J. d) The potential energy of the mass decreases by 5 J. e) The potential energy of the mass increases by 0.51 J. The potential energy of the mass decreases by 0.51 J g) There is no change in the energy of the mass. 3. A 5 kg box is pushed across a frictionless floor. A 15 kg rock is pushed the same distance by an identical force. Assuming each object starts from rest, which object has the most work done on it? Displacement Force Displacement Force 5 kg 13 Box Rock frictionless frictionless a) The box has the most work done on it. b) The rock has the most work done on it. c) They have the same most work done on it. d) We cannot tell without more specific information. 15 4. A force F pushes a box 2.0 m up a ramp that is inclined at 450. The force makes a 150 angle with respect to the surface of the ramp (as shown). How much work is done on the box? a) F(2.0 m) cos (300 d) F(2.0 m) cos (600) b) F (2.0 m (45) e) F(2.0 m) The work cannot be determined c) F(2.0 m) (15)Explanation / Answer
2)
work on mass = 15 J
speed of mass is constant so work will increase potential energy of mass.
option (a) is correct.
3)
work = force*displacement
here force and displacement are same for both objects so work done is same.
option (c) is correct.
4)
Work W = F*D*cos(theta)
theta is angle between force and displacement.
here component of Force at direction of displacement = Fcos(15)
so work done by force = Fcos(15)*D = F*(2.0)*cos(15)
option (c) is correct.