Question

Which situation would require the MOST work? A) 20 kg weight lifted 6 m B) 25 kg weight lifted 3 m C) 25 kg weight lifted 6 m D) 50 kg weight lifted 1 m

Answer 1

Work= force (N) x distance (m)

F= mass (kg) x acceleration (gravity; m/s^2)

for this question, your formula would be

Work= mass (kg) x acceleration (gravity) x distance (m)

a. F=20kg x 9.81 m/s^2 x6 m = 1177.2 J

b. F=25kg x 9.81 m/s^2 x3 m = 735.75 J

c. F=25kg x 9.81 m/s^2 x6 m = 1471.5 J

d. F=50kg x 9.81 m/s^2 x1 m = 490.5 J

Tip:

1. If this was a timed test, you could save some time by just multiplying the mass (kg) in the question by the distance because 9.81 is a constant in the formula, you can ignore it (+you're not asked for the final answer). c would still be the largest number
2. it would also help if you noticed:

• the distance in c is half that of b but the mass is the same.  eliminate b because c is obviously bigger
• a and c have the same distance but 25 is greater than 20; eliminate a