If a ball of mass 1 kg is released from a height of 4 m, its kinetic energy just before impact is closest to which value?

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Multiple Choice

If a ball of mass 1 kg is released from a height of 4 m, its kinetic energy just before impact is closest to which value?

Energy is conserved as the ball falls. The initial energy is gravitational potential energy mgh = 1 × 9.8 × 4 = 39.2 joules, and the ball starts with zero kinetic energy. As it descends, this potential energy is converted into kinetic energy, so just before hitting the ground the kinetic energy equals 39.2 J. That also corresponds to a speed of about sqrt(2gh) ≈ 8.86 m/s, giving KE = 1/2 mv^2 ≈ 39.2 J. The other options would reflect smaller heights or zero velocity, which don’t apply here.

Energy is conserved as the ball falls. The initial energy is gravitational potential energy mgh = 1 × 9.8 × 4 = 39.2 joules, and the ball starts with zero kinetic energy. As it descends, this potential energy is converted into kinetic energy, so just before hitting the ground the kinetic energy equals 39.2 J. That also corresponds to a speed of about sqrt(2gh) ≈ 8.86 m/s, giving KE = 1/2 mv^2 ≈ 39.2 J. The other options would reflect smaller heights or zero velocity, which don’t apply here.

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