he gravitational force between two objects of masses m1m1m_1 and m2m2m_2 that are separated by distance rrr is
1 answer:
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Answer:
e) True, f) False
Explanation:
e) Let consider a close system, that is, a system with no mass interactions with surroundings. Then, we get the following expression by the First Law of Thermodynamics:
(1)
Where:
- Net input heat, measured in joules.
- Net output work, measured in joules.
- Change in thermal energy, measured in joules.
Please notice that work comprises all kind of work (i.e. mechanical, electric, magnetic), whereas heat comprises all heat interactions including chemical and radioactive phenomena.
If thermal energy is released, then , which is caused by three scenarios:
(i) ,
,
(ii) ,
,
(iii) ,
In the case ,
, the thermal energy of the system is increased. Therefore, thermal energy is released during some energy conversions. Answer: True
f) A liquid solidifies when temperature goes below point of fusion, meaning a realease of heat with no work interactions. That is:
,
(2)
If , then
. Then, if a liquid absorbs heat energy, then thermal energy is increase and the liquid does not solidifies. Answer: False.
Answer:
3.25 seconds
Explanation:
It is given that,
A person throws a baseball from height of 7 feet with an initial vertical velocity of 50 feet per second. The equation for his motion is as follows :
Where
s is the height in feet
For the given condition, the equation becomes:
When it hits the ground, h = 0
i.e.
It is a quadratic equation, we find the value of t,
t = 3.25 seconds and t = -0.134 s
Neglecting negative value
Hence, for 3.25 seconds the baseball is in the air before it hits the ground.