Answer:
Efficiency = 90 %
Wasted energy = 10 %
Explanation:
Since we have the input energy and useful output energy of the electric kettle, the only thing we are required to calculate here is its efficiency. This is gotten from
E = useful output energy/input energy × 100
E = 9/10 × 100 = 90 %
The percentage of wasted energy is
W = wasted energy/input energy × 100
W = 1/10 × 100
W = 10 %
Answer:
acc. = 4-(-6) /5= 10/5=2 m/s^2
Answer:
The current is reduced to half of its original value.
Explanation:
- Assuming we can apply Ohm's Law to the circuit, as the internal resistance and the load resistor are in series, we can find the current I₁ as follows:
- where Rint = r and RL = r
- Replacing these values in I₁, we have:
- When the battery ages, if the internal resistance triples, the new current can be found using Ohm's Law again:
- We can find the relationship between I₂, and I₁, dividing both sides, as follows:
- The current when the internal resistance triples, is half of the original value, when the internal resistance was r, equal to the resistance of the load.
Answer:
D. The temperature does not change during a phase change because the average kinetic energy does not change. Therefore, the potential energy in the bonds between molecules must change.
Explanation:
When there is a change of state (for example, from solid into a liquid, as in this example), when energy is added to the system, the temperature of the substance does not change.
The reason for this is that the energy supplied is no longer used to increase the average kinetic energy of the particle, but instead it is used to break the bonds between the different particles/molecules. For instance, since in this case the substance is changing from solid to liquid, all the energy supplied during the phase change is used to break the bonds between the molecules of the solid: when the process is done, all the molecules will be free to slide past each other, and the substance has turned completely into a liquid.
The bonds between molecules store potential energy: therefore, this means that the energy supplied during the phase change is not used to change the kinetic energy, but to change the potential energy in the bonds between the molecules.
Force acting during collision is internal so momentum is conserve
so (initial momentum = final momentum) in both directions
Two cars collide at an icy intersection and stick together afterward. The first car has a mass of 1150 kg and was approaching at 5.00 m/s due south. The second car has a mass of 750 kg and was approaching at 25.0 m/s due west.
Let Vx is and Vy are final velocities of car in +x and +y direction respectively.
initial momentum in +ve x (east) direction = final momentum in +ve x direction (east)
- 750*25 + 1150*0 = (750+1150)
Vx
initial momentum in +ve y (north) direction = final momentum in +ve y direction (north)
750*0 - 1150*5 = (750+1150)
Vy
from here you can calculate Vx and Vy
so final velocity V is
<span>V=<span>(√</span><span>V2x</span>+<span>V2y</span>)
</span>
and angle make from +ve x axis is
<span>θ=<span>tan<span>−1</span></span>(<span><span>Vy</span><span>Vx</span></span>)
</span><span>
kinetic energy loss in the collision = final KE - initial KE</span>
