# What is the frequency of the car's vibration

Having trouble figuring out these 4 problems. I could use a walk through or an answer. thanks guys.

## Homework Statement

1a)When four people with a combined mass of 270 kg sit down in a car, they find that the car drops 1.00 cm lower on its springs. Then they get out of the car and bounce it up and down. What is the frequency of the car's vibration if its mass (when it is empty) is 2.0 103 kg?

b)An astronaut on a small planet wishes to measure the local value of g by timing pulses traveling down a wire which has a large object suspended from it. Assume a wire of mass 4.00 g is 1.60 m long and has a 3.00 kg object suspended from it. A pulse requires 38.3 ms to traverse the length of the wire. Calculate gplanet from these data. (You may neglect the mass of the wire when calculating the tension in it.)

c)A string is 41.0 cm long and has a mass of 3.00 g. A wave travels at 4.55 m/s along this string. A second string has the same length but one-fourth the mass of the first. If the two strings are under the same tension, what is the speed of a wave along the second string?

d)An aluminum clock pendulum having a period of 1.80 s keeps perfect time at 20.0?C. When placed in a room at a temperature of -5?C, it will gain time. How much time will it gain or lose every hour?

## The Attempt at a Solution

3) For question d, I used the equation for thermal expansion and got the new length. Then I set up a proportion for 1.8/3600 = 1.794/x. It was wrong :(

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