Part A: What magnitude of force must the worker apply to move the crate at const

Question

Part A: What magnitude of force must the worker apply to move the crate at constant velocity?
Express your answer using two significant figures.

Part B: How much work is done on the crate by this force when the crate is pushed a distance of 4.3 ?
Express your answer using two significant figures.

Part C: How much work is done on the crate by friction during this displacement?
Express your answer using two significant figures.

Part D: How much work is done by the normal force?

Part E: How much work is done by gravity?

Part F: What is the total work done on the crate?

Explanation / Answer

Let the Force be F. The pushing force F(p) must be equal to the friction force F(f)

Let the friction coeficient be: u. F(f)= u*(m*g+F*sin Q), where Q is the angle below the horisontal, m is the mass of the crate and g is the gravitation.

The Pushing force F(p)=F*cosQ

Therefore: F*cosQ = u*m*g+u*F*sinQ), or F*(cosQ-u*sinQ)=u*m*g, so: F=u*m*g/[cosQ-u*sinQ]

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