Answer:
-39.2m/s
Explanation:
Using the equation of motion;
v = u + at
Since the ball is thrown upward, the acceleration due to gravity acting on it will be negative, hence a = -g
v = u - gt
Since g = 9.8m/s²
t = 4.0s
u = 0m/s
v = 0 + (-9.8)(4)
v = 0 + (-9.8)(4)
v = -39.2m/s
Hence the speed of the ball before release is -39.2m/s
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Answer:
Work Done by the earth's gravitational force on the satellite as it travels from apogee to perigee is
W = F*D*Cos90° = 0
Explanation:
Although there is a change in the kinetic energy of the satellite at the apogee and perigee, the work done by the earth's gravitational force on the satellite is Zero.
W = F.D, F is the gravitational force, D is the displacement. Both F and D are vectors and perpendicular to each other. That is, the angle between F and D is 90°.
Answer: Option (a) is the correct answer.
Explanation:
Entropy is defined as the degree of randomness present in a substance. This means that more randomly the atoms in a substance are moving more will be entropy of the substance.
Entropy of a substance increases with increase in temperature.
For example, when a piece of wood is burned then its molecules will gain kinetic energy and hence, they start to move randomly from one place to another.
As a result, there will occur an increase in its entropy.
Thus, we can conclude that when a piece of wood is burned then its entropy increases.