A. Angular momentum is always conserved would be the correct answer.
This is because like linear momentum (mvmv), angular momentum (r×mvr×mv) is a conserved quantity, where rr is the vector from the center of rotation. For a skater holding a static pose, for each particle making up her body, the contribution in magnitude to the total angular momentum is given by mirivimirivi. Thus bringing in her arms reduces riri for those particles. In order to conserve angular momentum, there is then an increase in the angular velocity.
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The force ffrom the ground that holds the rock up and prevents her from falling through the gound, unless the ground breaks.
Use newton's second law, F = ma.
Force is 34 N and a is 4 m/s/s
34 = m(4), solve for m.
34/4 = 8.5 g
The initial temperature of the metal bolt is 80.8 °C
We'll begin by calculating the heat absorbed by the water.
- Mass of water (M) = 0.15 Kg
- Initial temperature (T₁) = 21 °C
- Final temperature (T₂) = 25 °C
- Change in temperature (ΔT) = T₂ – T₁ = 25 – 21 = 4 °C
- Specific heat capacity of water (C) = 4184 J/KgºC
Q = MCΔT
Q = 0.15 × 4184 × 4
Q = 2510.4 J
Finally, we shall determine the initial temperature of the metal bolt.
- Heat absorbed by water = 2510.4 J
- Heat released by metal (Q) = –2510.4 J
- Mass of metal (M) = 0.050 Kg
- Final temperature (T₂) = 25 °C
- Specific heat capacity of metal (C) = 899 J/Kg°C
- Initial temperature (T₁) =?
Q = MC(T₂ – T₁)
–2510.4 = 0.050 × 899 (25 – T₁)
–2510.4 = 44.95 (25 – T₁)
Clear bracket
–2510.4 = 1123.75 – 44.95T₁
Collect like terms
–2510.4 – 1123.75 = –44.95T₁
–3634.15 = –44.95T₁
Divide both side by –44.95
T₁ = –3634.15 / –44.95
T₁ = 80.8 °C
Thus, the initial temperature of the metal is 80.8 °C.
Learn more about heat tranfer:
brainly.com/question/26034272
