- #1

- 127

- 0

## Homework Statement

At the 2010 Winter Olympics, one of the most exciting events was the bobsleigh, in which teams of either two or four people on sleds hurtle down an icy half-pipe course at speeds that would be illegal on most highways. The track was 1450m long, with a total vertical drop of 152.

In an ideal run, the sled would never touch the sides of the course (in reality, glancing collisions are common). Assume a four-man sled, of total mass (sled+crew) 590kg is moving at 135km/hr down the course. It hits the side of the course at a shallow angle of 3.0°, and bounces off at the same angle, with its speed unchanged. The gouge marks on the side of the course (indicating the distance over the collision took place) are 35cm long. During the collision:

a. What is the change of momentum of the sled? (indicate both magnitude and direction of Δp)

b. What is the average force exerted on the sled (magnitude and direction)?

c. What is the acceleration of the sled, measured in units of g?

## Homework Equations

Δp=mΔu=I

## The Attempt at a Solution

I've finished the exercise but i'm not convinced of my answer. For a, i have that there are two momentum vectors in which the sled rebounds. By finding the resultant momentum (using vector subtraction), i figured out that the total momentum is 44000Ns and that its direction was to the right).

For b, i calculated the time at which the sleigh rebounded (quotient between skid marks and the velocity), and finally used I = FΔt to calculate the average force to be 4700kN (isn't this an extremely high value though?).

For c, i found the acceleration of the sleigh using the equation F = ma, calculating the final acceleration to be 880g (however, what about the acceleration due to gravity? Are we taking that into account?

Thank you very much.