Please help me

1.1. Which of the following is an example of simple harmonic motion?

1. The motion of a piston.

2. A ball bouncing on a sidewalk.

3. Calculating the angle of elevation for a building.

4. A police car shining a spotlight into buildings as it drives by.

Question

Please help me 

1.1. Which of the following is an example of simple harmonic motion?

1. The motion of a piston.

2. A ball bouncing on a sidewalk.

3. Calculating the angle of elevation for a building.

4. A police car shining a spotlight into buildings as it drives by.

ohohaye · Answer

I'm pretty sure that it is 2 but I'm not completely sure

wmj259 · Answer

http://en.wikipedia.org/wiki/Simple_harmonic_motion Look at the animation on the right hand side.

wmj259 · Answer

Notice how the pattern of motion is repeated over and over again. The movement of an object being affected by SHM (simple harmonic motion) should reach the same height over again......

ohohaye · Answer

So does that mean that it is number 3?

wmj259 · Answer

I am stuck between A and B.

ohohaye · Answer

Come to think of it, the bouncing of a ball on the sidewalk wouldn't always be the same every time, so maybe A?

wmj259 · Answer

I would say B because when the ball bounced it does not lose any energy in change of direction, such like a spring moving up and down or a pendulum as it repeats moving left to right to left.

ohohaye · Answer

ok, thank you