Posted by Anonymous on Monday, March 28, 2011 at 8:01pm.
1. A small fly of mass 0.26 g is caught in a spider's web. The web vibrates predominately with a frequency of 4.2 Hz. Find the effective spring stiffness constant k for the web. Hint: use natural frequency of oscillations formula.
N/m
2. At what frequency would you expect the web to vibrate if an insect of mass 0.52 g were trapped? Hint: use stiffness constant found in part 1. Hint: after the insect is trapped, the mass of the oscillator has increases by insect's mass, so the mass in the formula for natural frequency also has changed.
Hz
3. A spring scale being used to measure the weight of an object reads 12.8 N when it is used on earth. The spring stretches 4.95 cm under the load. The same object is weighed on the moon, where gravitational acceleration is
1/6g.
Find the reading of the spring scale on the moon.
Find the period for vertical oscillations of the spring on the moon.

physics (3 seperate questions)  drwls, Monday, March 28, 2011 at 8:41pm
(1) f = [1/(2 pi)]*(k/m)^1/2
Rearrange for k.
(2) With k staying the same, f drops a factor sqrt2 if the mass increases by a factor of 2.
(3) Spring scales measure weight, and weight = M g.
The scale reading decreases by a factor of 6. M stays the same and g decreases to 1/6 the value on Earth