Question
With winter approaching, you remember a sledding ride you had last winter. You started back from the edge of a hill, your friend pushed you with a 200 N force for a distance d of 2 m, and you then slid down the hill and went sliding out at the bottom. The hill had a total height h of 10 m. There was a friction force throughout your entire ride that was virtually constant at 50 N. Find your speed at the bottom of the hill, if the total distance x that you traveled was 50 m. Assume that your mass, with the sled, is 70 kg. Use conservation of work and energy.
(Picture below)
2.
Collisions
A ball, mass m1 = 2.0 kg, with an initial velocity of 2.0 m/s, strikes another ball, m2 = 4.0 kg, initially at rest. After an elastic collision, the first ball travels at a speed of 1.0 m/s at an angle of 30
1.With winter approaching, you remember a sledding ride you had last winter. You started back from the edge of a hill, your friend pushed you with a 200 N force for a distance d of 2 m, and you then slid down the hill and went sliding out at the bottom. The hill had a total height h of 10 m. There was a friction force throughout your entire ride that was virtually constant at 50 N. Find your speed at the bottom of the hill, if the total distance x that you traveled was 50 m. Assume that your mass, with the sled, is 70 kg. Use conservation of work and energy. (Picture below) 3. Torque The figure shows an arm holding a 10 lb ball. Calculate the net torque in order to find the force that the bicep must exert to hold the ball in this position. Follow the following steps: a. Choose an appropriate center of rotation for the arm.(Hint:Use the position where the force Fbone is acting.) b. Write the net torque acting on the arm from this center of rotation. c. Set the net torque equal to zero and find the bicep force Fbicep. (Picture below) 2. Collisions A ball, mass m1 = 2.0 kg, with an initial velocity of 2.0 m/s, strikes another ball, m2 = 4.0 kg, initially at rest. After an elastic collision, the first ball travels at a speed of 1.0 m/s at an angle of 30° with respect to the horizontal, as shown. a. What is the momentum of the center of mass of the two-ball system before the collision? b. What are the x and y components of the final velocity v2f of the second ball? c. What is the magnitude and direction (relative to the x-axis) of the final velocity of the second ball? (Picture below)
Explanation / Answer
F= 200 N, Fr is the frictional force is 50N, H = 10m, u = v = 0
change in P.E. = work done.
Increase in K.E.
Fw= mgh = 70
