If 56.5kJ are needed to raise the temp by 90°C and if the heater is 60% efficient that means that:
60% X y = 56.5kJ
where y is the electrical energy in kJ that the heater will use.
y = 94.2kJ
Answer:
1.127,56,000m
2. 347,600,000
3. 384,000
4. 200000000
5. 16,000,000cm
6. 36,000,000cm
7. 125,000m long, 400m deep, 1,500m wide
8. 11.18km/sec
9. 5,400,000
10. 2g
11. 1,200 mg to 2700 mg
12. 158000 kg
13. 450000000 mg
14. 23,000g to 90,000g
15. 40,000 ML
16. 1,000 ML
17. 26,600 KL
18. 1,558,000 L
19. 60 ML
20. 0.947
<span>The flywheel is solid cylindrical disc. Moment of inertial = ½ * mass * radius^2
Mass = 40.0 kg
Radius = ½ * 76.0 cm = 38 cm = 0.38 meter
Moment of inertial = ½ * 41 * 0.36^2
Convert rpm to radians/second
The distance of 1 revolution = 1 circumference = 2 * π * r
The number of radians/s in 1 revolution = 2 * π
1 minute = 60 seconds
1 revolution per minute = 2 * π radians / 60 seconds = π/30 rad/s
Initial angular velocity = 500 * π/30 = 16.667 * π rad/s
170 revolutions = 170 * 2 * π = 340 * π radians
The flywheel’s initial angular velocity = 16.667 * π rad/s. It decelerated at the rate of 1.071 rad/s^2 for 48.89 seconds.
θ = ωi * t + ½ * α * t^2
θ = 16.667 * π * 48.89 + ½ * -1.071 * 48.89^2
2559.9 - 1280
θ = 1280 radians</span>
Added potential energy = (mass) x (gravity) x (height)
or
Added potential energy = (weight) x (added height)
If you need to lift a 15N box 3m straight up, you have to increase its potential energy by (15 N) x (3 m) = 45 Joules .
Where is that added potential energy supposed to come from ? You could use an electric winch, a steam engine, a gasoline-powered motor, thousands of hamsters running on little treadmills that are are connected to the main pulley somehow, or your own arm muscles. But howEVER you do it, you have to provide <em>45 Joules</em> of WORK in order to increase the potential energy of the box by just that much.
