4. Suppose a block of mass m slides over a surface with kinetic friction coef- towards a spring with spring constant k. The block reaches the spring with spring with speed vo. ficient (a) How far is the spring compressed at maximum compression? Give your answer in terms of m, k, µk, and vo. (b) What is an expression for the maximum value that vo could be in order for the spring to remain maximally compressed, no matter what material the block and surface are? Give your answer in terms of m, k, pk. Hint: the coefficient of static friction is always greater than the coefficient of kinetic friction.

N 2. A horizontal spring is compressed by 25.0 cm. A 640.0 g box is then placed against the spring and then released. After travelling 3.15 m from the release point, the speed of the mass is 5.68 m/s. The coefficient of friction is 0.34. What is the spring constant of the spring? mi Tum Tm =

A 90-gram mass is placed on a vertically oriented spring that then is stretched 0.5 meters below its equilibrium position and released.  If the spring constant is 200 N/m, how fast will the mass be moving when it reaches the equilibrium position?  Hint:  You cannot ignore the change in gravitational potential energy in this problem.  Please give your answer in units of m/s, however, do not explicitly include units when typing your answer into the answer box.  Including actual units will result in your answer being incorrectly scored.

3. A 60 kg snowboarder begins to slide down the hill 50 m high on a smooth surface with a radius curvature of 80 m. The next section (AB) is a 20 m flat rough track with u = .3, at the end of which there is an elastic barrier with k = 1000 N/m. Find her speed at point A. b. How much work is done by frictional force? c. What is the maximum compression of the spring? d. Find the rate of heat dissipation along the section AB. e. How long does it take to cover the section AB? а. h k В