In the sport of skeleton a participant jumps onto a sled (known as

a skeleton) and proceeds to slide
down an icy track, belly down and
head first. In the 2010 Winter
Olympics, the track had sixteen turns
and dropped 126 m in elevation from
top to bottom. (a) In the absence of
nonconservative forces, such as friction and air resistance, what would be
the speed of a rider at the bottom
of the track? Assume that the speed at
the beginning of the run is relatively
small and can be ignored. (b) In reality, the gold-medal winner (Canadian
Jon Montgomery) reached the bottom
in one heat with a speed of 40.5 m/s
(about 91 mi/h). How much work was
done on him and his sled (assuming a
total mass of 118 kg) by nonconservative forces during this heat?
I successfully finished part a.) and came up with Vf=49.7m/s. Part b.)is where I need help.

b. work done (masshim+masssled)g*heightfell

Is that the PE which is conservative? The book states -4.89x10^4 J as the answer. The one proposed above yields -145706.4J.

Could the book be wrong?

To find the work done on the rider and his sled by nonconservative forces during the heat, we can use the work-energy principle, which states that the work done on an object is equal to the change in its kinetic energy.

The initial kinetic energy is assumed to be zero, so we can calculate the change in kinetic energy at the bottom of the track using the final speed found in part (a): Vf = 49.7 m/s.

The mass of the rider and the sled is given as 118 kg.

The formula to calculate kinetic energy is:

KE = (1/2)mv^2

Where KE is the kinetic energy, m is the mass, and v is the velocity.

Substituting the values:

KE = (1/2) * 118 kg * (49.7 m/s)^2

KE = 143,861.99 J

Now, we need to find the work done by nonconservative forces during the heat. Since the work done on an object is equal to the change in its kinetic energy, we can use the following equation:

Work = Change in Kinetic Energy

Work = KE - 0

Work = 143,861.99 J

Therefore, the work done on the rider and his sled by nonconservative forces during the heat is approximately 143,861.99 Joules.

To solve part b) of the problem, we need to calculate the work done on the rider and the sled by nonconservative forces during the heat. We can use the work-energy principle, which states that the work done on an object is equal to the change in its kinetic energy.

The initial kinetic energy (KEi) is zero because the question assumes that the speed at the beginning can be ignored. The final kinetic energy (KEf) can be calculated using the equation KEf = 1/2 * mv^2, where m is the total mass of the rider and the sled, and v is the final speed at the bottom of the track.

Given that the speed at the bottom of the track is 40.5 m/s and the total mass is 118 kg, we can substitute these values into the equation to find the final kinetic energy (KEf).

KEf = 1/2 * mv^2
KEf = 1/2 * 118 kg * (40.5 m/s)^2

Now, we need to find the change in kinetic energy (ΔKE) by subtracting the initial kinetic energy (KEi) from the final kinetic energy (KEf).

ΔKE = KEf - KEi
ΔKE = 1/2 * 118 kg * (40.5 m/s)^2 - 0

Finally, we can determine the work done on the rider and the sled by nonconservative forces by using the equation W = ΔKE.

W = ΔKE
W = 1/2 * 118 kg * (40.5 m/s)^2

Plugging in the values and solving the equation will give you the answer for part b).