What horizontally-applied force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight?
A) 2400 N
B) 2000 N
C) 600 N
D) 1600 N
E) none of these

Question

Quizplus · Accepted Answer

The weight of the crate is $400 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 3920 \, \text{N}$. Half of this weight is the friction force, which is $1960 \, \text{N}$. To accelerate the crate at $1 \, \text{m/s}^2$, the net force needed is $400 \, \text{kg} \times 1 \, \text{m/s}^2 = 400 \, \text{N}$. The total force required is the sum of the friction force and the net force needed for acceleration, which is $1960 \, \text{N} + 400 \, \text{N} = 2360 \, \text{N}$. The closest answer is $2400 \, \text{N}$.

What Horizontally-Applied Force Will Accelerate a 400-Kg Crate at 1