Sure !
The work is (weight of the book) x (height of the desk above the floor).
The force (weight) is the result of gravity.
It was gravity that did the work.
Answer:
a) 3.43 m/s
Explanation:
Due to the law of conservation of momentum, the total momentum of the bullet - rifle system must be conserved.
The total momentum before the bullet is shot is zero, because they are both at rest, so:

Instead the total momentum of the system after the shot is:

where:
m = 0.006 kg is the mass of the bullet
M = 1.4 kg is the mass of the rifle
v = 800 m/s is the velocity of the bullet
V is the recoil velocity of the rifle
The total momentum is conserved, therefore we can write:

Which means:

Solving for V, we can find the recoil velocity of the rifle:

where the negative sign indicates that the velocity is opposite to direction of the bullet: so the recoil speed is
a) 3.43 m/s
Answer:
- 21.3 kJ
Explanation:
For the favorable reaction, ΔG₁ = + 9.2 kJ (ΔG > 0 for unfavorable reaction)
For the favorable reaction, ΔG₂ = - 30.5 kJ (ΔG < 0 for favorable reaction)
For the overall reaction, ΔG = ΔG₁ + ΔG₂ = + 9.2 kJ + (- 30.5 kJ)
ΔG = + 9.2 kJ - 30.5 kJ = - 21.3 kJ
Answer:
b. The speed of light is 2.99792458 x 10^8 meters/second.
Explanation:
Speed of light is a universal constant and its value is same throughout the universe . So alien living near Alpha Centauri will quickly understand about it . But other statements are not universal . Mass of electron can vary as per relativistic formula of Einstein . Similarly , mass of proton can also vary according to relativistic concept . It depends upon the velocity of particle . So, the ratio of mass of proton and mass of electron will also vary from one star to another .