A book is being pushed across a horizontal table. Does the normal force pushing up on the book do any work on it? O Yes, because the force of gravity is opposing the normal force on the book. O No, because no part of the book's motion is in the same direction as the normal force. O No, because normal forces cannot ever do work. O Yes, because the normal force is acting on the book as the book is moving.

Early one October, you go to a pumpkin patch to select your Halloween pumpkin. You lift the 3.0 kg pumpkin to a height of 1.3 m , then carry it 50.0 m (on level ground) to the check-out stand. Calculate the work you do on the pumpkin as you lift it from the ground. How much work do you do on the pumpkin as you carry it from the field?

A force F = bx^3 acts in the x direction, where the value of b is 3.33 N/m3. How much work is done by this force in moving an object from x = 0.00 m to x = 2.06 m? Give your result in Joules to three significant figures.

A box m = 89 kg is being pulled by a constant force F = 124 N at an angle of θ = 38 degrees. The initial speed of the box is zero. a)Write an expression for the work done by force F as the block moves a horizontal distance d.  b)How much work, in joules, was done in moving the block 6.9 m?  c)What is the speed of the box at d = 6.9 m if the surface is frictionless?

Your friend is pushing a crate. The crate is so heavy of 120 kg of mass that it is moving very slowly at 2 m/s speed. Later you help your friend. Now the box is moving at 5 m/s speed. How much work have you and your friend together done?

A child throws a stone upwards. While the stone is moving upwards the gravitational force does positive work on it and the gravitational potential energy increases. the gravitational force does positive work on it and the gravitational potential energy decreases. the gravitational force does negative work on it and the gravitational potential energy increases. O the gravitational force does negative work on it and the gravitational potential energy decreases.

A large object moves to the right across a horizontal surface. The figure depicts five forces acting on the object, each with the same magnitude but exerted in different directions. For each one,  a) determine whether the work done is positive or negative. b) Students were asked to rank the work done by the forces with the greatest first. Here is what one student was thinking: “I know that since W=Fcos, the more the force pushes in the direction that the object moves, the more work done. So, I think that F1 does the most work, but I am not sure about F2 and F5. The angle for both is the same, but they are pointing in different directions. I know that the sign for vectors just means direction and not size, but I am not sure here.” How would you explain the meaning of the sign for Work? How would you Rank the Work done?

A man starts at ground level and carries a 20 kg box up a flight of stairs to a height of 3.6 m. He then carries the box down an adjacent flight of stairs back to ground level and ends up 10 m away from where he started. What is the total amount of work the man has done? Explain

When a book slides along a tabletop, the force of friction does negative work on it. Can friction ever do positive work? Explain. (Hint: Think of a box in the back of an accelerating truck.)

Can the normal force on an object ever do work? Explain.