A screw has a pitch equal to 0.5 mm. What should be the number of division on its head so as to read correct up to 0.001mm with its help?

The pendulum used in a clock is:

1. Simple pendulum
2. Compound pendulum
3. Second pendulum
4. None of these

A simple pendulum is made by suspending a bob of mass 1 kg by a string of length l. Now if the length of this pendulum is increased to 4l, then its time period T will :

1. remain the same
2. become twice
3. become four times
4. become half

The time period of a seconds' pendulum clock is —

1. 1 s
2. 2 s
3. 1 min
4. 12 h