Question

9.) a horizontal force of 100 n is required to push a crate across a factory floor at a constant speed. what is the net force acting on the crate? what is the force of friction acting on the crate?
10.) a 10 kg box is pushed along a horizontal floor with a force of 50 n to the right. the friction force is acting on the box is 20 n to the left. what is the acceleration of the box? be sure to include the direction of the acceleration.

Explanation:

For Question 9:

Step1: Analyze constant speed condition

An object moving at constant speed has zero acceleration, per Newton's first law.

Step2: Calculate net force

Using Newton's second law $F_{net}=ma$, where $a=0$.
$F_{net}=m \times 0 = 0$ N

Step3: Relate applied and friction force

Since $F_{net}=F_{applied}+F_{friction}=0$, rearrange to solve for friction.
$F_{friction}=-F_{applied}=-100$ N (negative sign indicates opposite direction to applied force)

Step1: Calculate net horizontal force

Subtract friction from applied force (right = positive direction).
$F_{net}=F_{applied}-F_{friction}=50\ \text{N} - 20\ \text{N}=30\ \text{N}$ (to the right)

Step2: Solve for acceleration

Use Newton's second law $a=\frac{F_{net}}{m}$, substitute values.
$a=\frac{30\ \text{N}}{10\ \text{kg}}=3\ \text{m/s}^2$

Answer:

Net force on the crate: 0 N
Force of friction on the crate: 100 N (opposite to the direction of the applied horizontal force)

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For Question 10: