A crate of mass 40 kg is pushed across a horizontal concrete floor with a horizontal force of 150 N. If a constant frictional force of 70 N opposes the motion, what is the acceleration of the crate?
Answer and explanation
Correct answer: A. 2.0 m/s^2
- Step 1: Calculate the net force: F_net = F_applied - F_friction = 150 N - 70 N = 80 N. Step 2. Apply F_net = m a => a = F_net / m = 80 / 40 = 2.0 m/s^2. Answer: 2.0 m/s^2. Why not the others:* Ignoring friction gives 150/40 = 3.75 m/s^2.
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