Answer: A
Hope this help you!!
Answer:
187 J
Explanation:
First Law of Thermodynamics :
ΔQ = ΔW + ΔU
ΔQ : Heat. If it added to system then positive and if it is rejected by system then negative.
ΔW : Work. If it done by the system then positive and if it is done on system then negative.
ΔU : Internal Energy. If it positive then temperature of system increased and if it is negative then temperature of system decreased.
ΔQ = 79 J
ΔW = - 108 J
ΔU = ?
substituting the value in the equation:
79 = -108 + ΔU
∴ ΔU = 187 J
The acceleration of gravity on or near the surface of the Earth is 9.8 m/s².
Anything acted on only by gravity loses 9.8 m/s of upward speed, or gains
9.8 m/s of downward speed, every second.
Leaping straight upward at 1.8 m/s, Tina keeps rising until she runs out of
upward speed. That happens in (1.8/9.8) = 0.1837 second after the leap.
After that, Finkel's First Law of Motion takes over:
"What goes up must come down."
The dropping part of the leap is symmetrical with the first. Please don't
make me go through proving it. Tina hits the floor at the same speed of
1.8 m/s with which she left it, and it takes the same amount of time to drop
from the peak to the floor as it took to rise from the floor to the peak.
So her total time out of contact with the floor is
2 x (0.1837 sec) = 0.367 second (rounded)
