Abicyclist rides 1.94 km due east, while the resistive force from the air has a magnitude of 7.92 n and points due west. the rider then turns around and rides 1.94 km due west, back to her starting point. the resistive force from the air on the return trip has a magnitude of 7.92 n and points due east. find the work done by the resistive force during the round trip.

Negative work done of 30729.6 Joules

Explanation:

Since work done is dot product of force and displacement. so,

W= F.d

W= F d cosΘ

where Θ is the angle between force and displacement. Since resistive force and displacement makes an angle of 180 (as one is pointed east and other west). So,

W = (7.92)(1940)(cos (180))     (distance should be in meter)

W = 15364.8(-1)

W = -15364.8 (for going east)

Total work done will be twice of that as the resistive force and distance are same for the way back.

W = -15364.8 + (-15364.8)

W = -30729.6 Joules

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j

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