Answer:
E) 1500 N
Step-by-step explanation:
There are two ways to solve this: energy equations or kinematics.
First I'll use energy equations.
All of Santa's energy is converted to work by friction.
Initial energy = final energy + work
PE = W
mgh = Fd
(120 kg) (9.8 m/s²) (9 m + 2 m) = F (9 m)
F = 1437 N
Using kinematics, the velocity Santa reaches when he reaches the chimney is:
v² = v₀² + 2a(x - x₀)
v² = (0 m/s)² + 2 (-9.8 m/s²) (9 m - 11 m)
v = -6.26 m/s
Then he starts decelerating down the chimney. Finding the acceleration:
v² = v₀² + 2a(x - x₀)
(0 m/s)² = (-6.26 m/s)² + 2 a (0 m - 9 m)
a = 2.18 m/s²
Sum of the forces acting on Santa:
∑F = ma
F - W = ma
F = W + ma
F = mg + ma
F = m (g + a)
F = (120 kg) (9.8 m/s² + 2.18 m/s²)
F = 1437 N
Rounded to 2 sig-figs, that's 1400 N, which isn't one of the choices. But if we use 10 m/s² for g instead of 9.8 m/s², we get F = 1467 N, which rounds to 1500 N.
E) 1500 N