The speed of sound on steel is about 5000 m/s. A friend of yours, 2000 m away, strikes a railroad track which you have your ear on. How long after she strikes it will the sound arrive?

t = 0.4 s

Explanation:

Given that,

The speed of sound on steel is about 5000 m/s.

A friend of yours, 2000 m away, strikes a railroad track which you have your ear on.

We need to find the time after she strikes it will the sound arrive. Let the time is t. We know that,

Speed = distance/time

So,

So, the required time is 0.4 seconds.

c.the charges if the proton and electron and gravity

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.