Apendulum with a mass of 0.100 kg was released. the string made a
7.0° angle with the vertical. the bob of the pendulum returns to its lowest point
every 0.10 s.
what is its period? what is its frequency?

The bob passes the lowest point twice during every complete swing.

The period of this pendulum is 0.2 seconds.

Frequency = 1/period

Frequency = 1/0.2 sec

Frequency = 5 Hz.  (A very very very short, fast pendulum.)

Note:  

The mass of the bob, the angle from the vertical (as long as it's small), the color of the string, and the day of the week have no effect on the period.  Only the length of the string has.

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

a person with a mass of 106kg has a weight of 1060n