1. Nov 3, 2009

ispyy

1. A spring has a force constant of 30000 N/m.
How far must it be stretched for its poten-
tial energy to be 47 J?
Answer in units of m.

2. A bobsled slides down an ice track starting
(at zero initial speed) from the top of a(n)
94.5 m high hill.
The acceleration of gravity is 9.8 m/s2 .
Neglect friction and air resistance and de-
termine the bobsled’s speed at the bottom of
the hill.
Answer in units of m/s.

3. An ore car of mass 40000 kg starts from rest
and rolls downhill on tracks from a mine. At
the end of the tracks, 9.4 m lower vertically,
is a horizontally situated spring with constant
4.5 × 105 N/m.
The acceleration of gravity is 9.8 m/s2 .
Ignore friction.
How much is the spring compressed in stop-
ping the ore car?
Answer in units of m.

4. A roller coaster cart ofmassm = 336 kg starts
stationary at point A, where h1 = 27.7 m and
a while later is at B, where h2 = 13.3 m.
The acceleration of gravity is 9.8 m/s2 .
What is the speed of the cart at B, ignoring
the effect of friction?
Answer in units of m/s.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution