Physics NYA Problem Set 8 Energy Instructor: Maria Mastorakos 1. A block slides starts from rr t and slides down the ramp and compresses the spring shown by 0.220 m. There is no friction between any surfaces. a) At what distance from the bottom of the ramp did the block start? b) How fast is the block going right before it hits the spring? k400 N/m m- 200 kg 37.0 k-0.220 m- 2. In the movie Monty Python and the Holy Grail a cow is catapulted from the top of a castle wall over to the people down below. The gravitational potential energy is set to zero at ground level. The cow is launched from a spring of spring constant 1.1x10 N/m that is compressed 0.5 m from its re ting length. If the castle is 9.1 m tall and the mass of the cow is 110 kg, a) what is the gravitational potential energy of the cow at the top of the castle? b) What is the elastic spring energy of the cow before the catapult is released? c) What is the speed of the cow right before it lands on the ground? A 3. A small block of mass 200 g starts at rest at A, slides to B where its speed is ve = 8 m/s then slides along the horizontal surface a distance 10 m before coming to rest at C. a) What is the work of friction along the curved surface? b) What is the coefficient of kinetic friction along the horizontal surface? 4.0 m B 10 m 4. A block of mass 500g is attached to a spring of spring constant 80 N/m (see the figure). The other end of the spring is attached to a support while the mass rests on a rough surface with a coefficient of friction of 0.20 that is inclined at angle of 30°. The block is pushed along the surface till the spring compresses by 10 cm and is then released from rest. a) How much potential energy was stored in the block-spring-support system when the block was just released? b) Determine the speed of the block when it crosses the point when the spring is neither compressed nor stretched. c) How far up the incline from the initial compressed position does the mass come to rest? www 30