Question

An applied force of 875 N (up) acts on a 4.63 kg mass over a displacement of 4.80m (up). Assuming that no friction is involved in this movement, what is the change in kinetic energy of the mass?

Answer 1

Answer on Question #43394 – Physics - Mechanics | Kinematics | Dynamics

An applied force of 875 N (up) acts on a 4.63 kg mass over a displacement of 4.80m (up). Assuming that no friction is involved in this movement, what is the change in kinetic energy of the mass?

Solution:

F = 875N – applied force;

m = 4.63 kg – mass of the object;

s = 4.8 m – displacement of the mass;

ΔEKE – change in kinetic energy of the mass;

ΔEPE – change in potential energy of the mass;

The work done by applied force changes the total mechanical energy of the mass:

Work = Change in Total Mechanical Energy

W = ΔEKE + ΔEPE (1)

ΔEPE = mg(h₂ - h₁) = mgs (2)

W = F · s · cos θ = F · s · cos 90° = F · s (3)

(3)and(2)in(1):

F · s = mgs + ΔEKE

ΔEKE = F · s - mgs = 875N · 4.8m - 4.63kg · 9.8 N/kg · 4.63m = 3990 J

Answer: change in kinetic energy of the mass is equal to 3990 J.

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