Apendulum and a block hanging at the end of a spring are both carefully adjusted to make one vibration per second while on the earth's surface. will the period of vibration of the pendulum or of the block on a spring be affected if they are moved to the moon?

For  the pendulum , yes and for the spring ,No

Explanation:

We will examine the two cases,

For pendulum;

we see that for a pendulum, the period depends on the gravitational acceleration of the region it is. so the period for earth will differ compared to that of the moon.

For a spring;

form the equation above is obvious that the period of a spring in vibration is independent of gravitational acceleration of the region it is.

The reason for the differences in density is the composition of rock in the plates. When two plates come in contact with each other through plate tectonics, scientists can use the density of the plates to predict what will happen. Whichever plate is more dense will sink, and the less dense plate will float over it.

Explanation:

Hope this helps ( not copied and pasted, this answer was done by me so I don't know if it's good or not)