- #1

- 4

- 1

- Homework Statement
- A force of 300 N is applied to a 20 kg crate at an angle of 30o below the horizontal. Determine the acceleration of the crate as it moves along the horizontal surface. The coefficient of friction between the crate and the surface µk is 0.50.

1. 17.2

2. 8.6 (My choice but it's incorrect)

3. 4.3

4. 9.8

- Relevant Equations
- Fg = mg

μ = Ff / Fn

F = ma

First of all, the pulling force is

300N cos(30) = 260 N

At this point, I try to find the friction force

Fn = mg = 20kg * 9.81 m/s^2 = 196.2 N

Then,

Ff = μ * Fn = 0.5 * 196.2 N = 98.1 N

So after canceling the horizontal forces,

260N - 98.1N = 161.9N

And the acceleration will be 161.9N / 20kg = 8.1 m/s ^2

Since 8.6 is the closest I choose 8.6, but it's incorrect.

300N cos(30) = 260 N

At this point, I try to find the friction force

Fn = mg = 20kg * 9.81 m/s^2 = 196.2 N

Then,

Ff = μ * Fn = 0.5 * 196.2 N = 98.1 N

So after canceling the horizontal forces,

260N - 98.1N = 161.9N

And the acceleration will be 161.9N / 20kg = 8.1 m/s ^2

Since 8.6 is the closest I choose 8.6, but it's incorrect.