Answer to Question #162480 in Classical Mechanics for pat

Question

A 320 N crate is pulled across a rough floor with a force of P=150 N as shown. The coefficient of kinetic friction between the crate and the ground is 0.30.

(a) Draw a free body diagram of the crate on a separate page.

(b) What are the normal and frictional forces acting on the crate?

(c) What is the acceleration of the crate?

Answer 1

a)

b)

$$N=W=320\ N\\F_f=\mu N=(0.3)(320)=96\ N$$

c)

$$ma=\frac{W}{g}a=F-F_f\\\frac{320}{9.8}a=320-96\\a=6.9\frac{m}{s^2}$$