To move a large crate across a rough floor, you push on it with a force at an angle of 15 degrees below the horizontal. Find the force necessary to start the crate moving, given that the mass of the crate is 32 kg and the coefficient of static friction between the crate and the floor is 0.49.

663N

Explanation:

We need to find the force that will overcome the frictional force.

The angle of the normal force is 15°.

The mass of the crate is 32 kg

The coefficient of static friction is 0.49

Frictional force is given in terms of Normal force as:

F = μNcosθ

where μ = coefficient of static friction

N = normal force

θ = angle of normal force

Frictional force is given as:

F = mg

=>mg = μNcosθ

=> N = mg / (μcosθ)

N = (32 * 9.8) / (0.49 * cos15)

N = 313.6 / 0.473

N = 663 N

The force needed to cause the box to move must be 663N or greater.