An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. But she does have devices to measure distance and time accurately. She knows her own mass is 78.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. When this canister is approaching her at 3.40 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.50 m/s. What is the mass of this canister?

93.33 kg

Explanation:

We are given that

Mass of astronaut=m'=78.4 kg

Initial velocity of canister,u=3.4 m/s

Final velocity of canister,v=1.3 m/s

Initial velocity of astronaut=u'=0

Final velocity of astronaut,v'=2.5 m/s

We have to find the mass of canister.

According to law of conservation of momentum

Using the formula

Mass of canister=93.33 kg

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.

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