A12-kg sled is moving at a speed of 2.0 m/s. at which of the following speeds will the sled have twice as much kinetic energy? a. 2.8 m/s b. 4.2 m/s c. 6 m/s d. none of the above

2.8 m/s

Explanation:

Kinetic energy is the energy possessed by a body due to virtue of its motion - speed.

K.E. = 0.5 m v²

mass, m = 12 kg

speed, v = 2.0 m/s

K.E. = 0.5 × 12 × 2.0² = 24 J

For kinetic energy to be twice of the initial i.e. (24×2 = 48 J), the speed must be

48 J = 0.5 × 12× v'²

Thus, at speed 2.8 m/s, the sled would have twice amount of kinetic energy.

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