How do i do number 60? (the clown question)

310 N

Explanation:

Draw a free body diagram of the clown.  There are five forces:

Tension force T pulling up.

Normal force N pushing up.

Weight force W pulling down.

Tension force T pulling left.

Friction force Nμ pushing right.

Sum of the forces in the y direction:

∑F = ma

N + T − W = 0

N = W − T

Sum of the forces in the x direction:

∑F = ma

Nμ − T = 0

T = Nμ

Substitute and solve for T:

T = (W − T)μ

T = Wμ − Tμ

(1 + μ) T = Wμ

T = Wμ / (1 + μ)

Plug in values and solve:

T = (890 N) (0.53) / (1 + 0.53)

T ≈ 310 N

The clown must pull with at least 310 N to yank his feet out from under himself.