Problem Solving                                                            Brockport High School NY USA
Physics                                                                            Mr Keefer

1.  A spring has a force constant (k) of 22.0 N/m.  If it oscillates with an amplitude (A) of 87.0 mm, what is the mechanical energy (M.E.) of the spring?

2.  A block with a mass of 0.47 kg is on a harmonic spring whose force constant (k) is 23.0 N/m.  While in motion, its mechanical energy is 0.025 J.  What is the amplitude and maximum speed of the block during the oscillation (ignore the mass of the spring).

3.  A common flea (Pulex irritans, Phylum Arthropoda; Order Siphonaptera) has a mass of 200.0 mg.  It can jump approximately 20 cm straight up.  Ignoring air resistance, determine the following for the flea:
a)  weight
b)  initial velocity
c)  time of flight
d)  initial momentum
e)  initial kinetic energy
f)  maximum gravitational potential energy
g)  its kinetic energy and potential energy half way up
h) what is the mechanical energy of the falling flightless flea in flight five cm from the floor?

4.  The speed limit along a portion of Redman Road is 25 m/s.  To stop at a stop sign, a 17 year old driving the car slams on the brakes causing the car to slide 57.0 m before coming to a stop.  The coefficient of friction, μk, between the road and the tires is 0.80.  A police officer watching the intersection begins writing a speeding ticket.  Should the driver contest the ticket in court?

5.  Use logical statements to explain the following:
a)  A woman lets go of her brief case in an elevator but it does not fall to the floor.
b)  A spring with a force constant of 20 N/m is cut in half.  What is its force constant after the cut?
c)  A pendulum clock is placed on an elevator.  How does its period T change as the elevator goes up and down?

Back to the Brockport High School Science Department