Question

A 343 kg box is pulled 9.00 m up a 30° frictionless, inclined plane by an external force of 5125 N that acts parallel to the plane. Calculate the work done by the external force. work done by the external force: J Calculate the work done by gravity. work done by gravity: J Calculate the work done by the normal force. work done by the normal force:

Answer 1

Answer:

a) work done by external force = 7920.765 N

b) work done by gravity = 15141.735 J

c) 0 N

Explanation:

mass of box = 343 kg

weight of box = mass x acceleration due to gravity = 343 x 9.81 m/s^2 = 3364.83 N

length of incline = 9 m

angle of incline = 30°

external force = 5125 N

a) work done by external force

resultant force = external force - weight of box = 5125 - 3364.83 = 1760.17 N

work done by external force = resultant force x vertical distance up

work done by external force = 1760.17 x 9 sin 30° = 7920.765 N

b) work done by gravity = work done against gravity

length of incline = 9 m

we resolve to the vertical distance = 9 x sin 30° = 4.5 m

work done by gravity = weight of box x vertical height = 3364.83 x 4.5 = 15141.735 J

c) work done by the normal force

since there is no  work done in the direction perpendicular to the plane, work done by the normal force = 0 N