Question

Sarah is hanging a 1.5 -kg picture on the wall. She holds it in place with a horizontal force while she checks to see if it is positioned correctly. The coefficient of static friction between the picture and the wall is 0.6. Find the minimum force that stash needs to apply in order to prevent the picture form falling?

Answer 1

Answer:

24.5 N

Explanation:

Draw a free body diagram of the picture.  There are four forces:

Weight force mg pulling down.

Friction force Nμ pushing up.

Normal force N pushing left.

Applied force F pushing right.

Sum of the forces in the y direction:

∑F = ma

Nμ − mg = 0

N = mg / μ

Sum of the forces in the x direction:

∑F = ma

F − N = 0

F = N

Substitute and solve:

F = mg / μ

F = (1.5 kg) (9.8 m/s²) / (0.6)

F = 24.5 N