A factory worker is pushing a large box of cookies across a level horizontal portion of the factory floor. Four forces are acting on the box: the pushing force exerted by the factory worker (Fp), the weight of the box (Fg), the normal force exerted by the floor (Fn), and the kinetic frictional force (Fr). Determine whether the work done by each of these forces is positive, negative, or zero. We start with the assumption that the box is pushed to the right. We also assume that the box moves with constant velocity so that the forces are in equilibrium. The force diagram for this problem is:

A factory worker is pushing a large box of cookies across a level horizontal portion of the factory floor. Four forces are acting on the box: the pushing force exerted by the factory worker (Fp), the weight of the box (Fg), the normal force exerted by the floor (Fn), and the kinetic frictional force (Fr). Determine whether the work done by each of these forces is positive, negative, or zero. We start with the assumption that the box is pushed to the right. We also assume that the box moves with constant velocity so that the forces are in equilibrium. The force diagram for this problem is:

International Edition---engineering Mechanics: Statics, 4th Edition

4th Edition

ISBN:9781305501607

Author:Andrew Pytel And Jaan Kiusalaas

Publisher:Andrew Pytel And Jaan Kiusalaas

Chapter7: Dry Friction

Section: Chapter Questions

Problem 7.78P: The figure shows a steel bar being processed by a rolling mill. Given that P=80kN and r =0.016,...

See similar textbooks

Similar questions

Repeat Prob. 4.152 assuming that the 400-kN force is applied at O instead of L.
Draw the FBD of the entire frame, assuming that friction and the weights of the members are negligible. How many unknowns appear on this FBD?
Find the tension T in the cable when the 180-N force is applied to the pedal at E. Neglect friction and the weights of the parts.
Calculate the horizontal force P required to push the 85-lb lawn mower at constant speed. The center of gravity of the mower is at G, and the coefficients of rolling resistance are 0.12 for the front wheels and 0.18 for the rear wheels.
Problem 4 - Does the car make it? A 3.2-kg toy car, initially moving at 5.0 m/s, at a height of 4.0-m encounters a hill of he
The air temperature inside a hot-air balloon is 80oC, while the surrounding atmospheric air temperature is only 15oC. The mass of the empty-balloon material is 10 kg. When inflated completely, the volume of hot air within the balloon is 5000 m3 . Determine the maximum mass of the load that the balloon can lift from the ground in this situation. Given: ρair (at 15oC) = 1.22 kg/m3 , ρair (at 80oC) = 1.01 kg/m3 . If only 80% of the maximum load mass is used, what would be the balloon’s initial acceleration upward (neglecting any air drag effect)?
A boat having a mass of 80 Mg rests on the bottom of the lake and displaces 11.75 m^3 of water. Since the lifting capacity of the crane is only F = 550 kN, two balloons are attached to the sides of the boat and filled with air. The volume of a sphere is V =4/3πr^3. ρw = 1000 kg/m^3.Determine the smallest radius r of each spherical balloon that is needed to lift the boat. Neglect the mass of air and of the balloon for the calculation required for the lift and What is the mass of air in each balloon if the air and water temperature is 12∘C? The balloons are at an average depth of 20 mm. The gas constant for air is R= 286.9 J/(kg⋅K)
The small piston of a hydraulic lift has a cross-sectional area of 3.00cm^2,and its large piston has a cross-sectional area of 200cm^2.What downward force of magnitude F1 must be applied to the small piston for the lift to raise a load whose weight is Fg= 15.0kN?
A piano mover rolls a 200 kg piano at constant speed up a ramp 2m long at an angle of 30 degrees with the horizontal. a) What force does he apply to the piano?, b) How much work does he do? Include given, fbd and solution
The platform P, shown in Fig. has negligible mass and is tied down so that the 0.4 m long cords keep a 1m long spring compressed 0.6 m when nothing is on the platform. If a 2-kg block is placed on the platform and released from rest after the platform is pushed down 0.1 m, determine the maximum height h the block rises in the air, measured from the ground.
. The small piston of a hydraulic lift (g. 1) has a cross-sectional area of 3.00cm2, and its large piston has a cross-sectional area of 200cm2. What downward force of magnitude F1 must be applied to the small piston for the lift to raise a load whose weight is Fg = 15.0kN?
A man is standing on a board on a frozen lake where there is no friction between the board and the ice surface. Tha man's mass is 2 m and the boaf's mass is 4 m. The board has length L. He walks from 1/5 Lfrom the left end of the board to 1/5 L from the right end of the board. How far and in which direction does the board move during this process?