Question

Difficulty: MediumMechanics and Motion

A warehouse forklift applies a constant horizontal forward force of 300 N300\text{ N} to a 120 kg120\text{ kg} cargo pallet moving across a level floor. A constant opposing friction force of 60 N60\text{ N} acts against the pallet. What is the magnitude of the pallet's acceleration in m/s2\text{m/s}^2?

Answer: 2 m/s^2

Answer

The magnitude of the pallet's acceleration is 2 m/s22\text{ m/s}^2.
According to Newton's second law of motion, the acceleration of an object equals the net unbalanced force acting upon it divided by its mass (a=Fnetma = \frac{F_{\text{net}}}{m}). The net force is the forward applied force minus opposing friction (300 N−60 N=240 N300\text{ N} - 60\text{ N} = 240\text{ N}). Dividing 240 N240\text{ N} by the mass of 120 kg120\text{ kg} yields an acceleration of 2 m/s22\text{ m/s}^2.

Step-by-Step Solution

1
Determine the net horizontal force acting on the object by combining all horizontal force components.
Fnet=Fapplied−Ffriction=300 N−60 N=240 NF_{\text{net}} = F_{\text{applied}} - F_{\text{friction}} = 300\text{ N} - 60\text{ N} = 240\text{ N}
Forces in opposite directions subtract to yield the overall resultant force causing acceleration.
2
Use Newton's second law (Fnet=m⋅aF_{\text{net}} = m \cdot a) to solve for acceleration (aa).
a=Fnetm=240 N120 kg=2 m/s2a = \frac{F_{\text{net}}}{m} = \frac{240\text{ N}}{120\text{ kg}} = 2\text{ m/s}^2
Acceleration is directly proportional to net force and inversely proportional to mass.

Key Concept

Newton's Second Law of Motion (Fnet=maF_{\text{net}} = ma) with opposing frictional forces
Estimated Time:1m 0s
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