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Two objects were lifted by a machine One object had a mass of 2 kilograms, and was lifted at a speed of 2 m/sec. The other had a mass of 4 kilograms and was lifted at a rate of 3 m/sec.

a. Which object had more kinetic energy while it was being lifted?

1 Answer

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Final answer:

Object 2, with a mass of 4 kilograms and lifted at a speed of 3 m/sec, has more kinetic energy (18 J) compared to object 1, which has 4 J of kinetic energy.

Step-by-step explanation:

Kinetic Energy of Two Lifted Objects

To determine which object has more kinetic energy while being lifted, we use the formula for kinetic energy (KE):
KE = ½ mv², where m is the mass of the object and v is its velocity. Calculating the kinetic energy for each object:

For object 1 (mass = 2 kg, velocity = 2 m/s):
KE1 = ½ × 2 kg × (2 m/s)² = 4 J

For object 2 (mass = 4 kg, velocity = 3 m/s):
KE2 = ½ × 4 kg × (3 m/s)² = 18 J

Comparing the two values, object 2 has a higher kinetic energy of 18 J compared to object 1's kinetic energy of 4 J. Therefore, object 2 has more kinetic energy while being lifted.

The principle behind this is straightforward: kinetic energy depends on both the mass and the square of the velocity of an object. This explains why, despite object 2's slower rate of increase in velocity, it has more kinetic energy due to its greater mass.

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