Question

4. Two objects were lifted by a machine. One object had a mass of 2 kilograms, and was lifted a t a speed of 2 m/sec. The other had a mass of 4 kilograms and was lifted at a rate of 3 m/sec.
Question a. Which object had more kinetic energy while it was being lifted?

Question b. Which object had more potential energy when it was lifted to a distance of 10 meters? Show your calculation.

Answer 1

Explanation:

a) Case1, by the formula, ke=½mv².

m=2kg, v=2m/s

ke = ½×2×2² = 4J

Case2, by the formula, ke=½mv².

m=4kg, v=3m/s

ke = ½×4×3² = 18J

therefore, the second object has more kinetic energy.

b) Case1, by the formula, pe = mgh

m=2kg, g=9.8m/s²(not given)(can consider 10m/s² when given), h= 10m

Pe1(write 1 in subscript) = 2×9.8×10= 196J.

Case2, by the formula, pe = mgh

m=4kg, g=9.8m/s²(not given)(can consider 10m/s² when given), h= 10m

Pe2(write 2 in subscript) = 4×9.8×10= 392J.

so, the object 2 has more potential energy.

hope this helps you.