2/A mains electricity hairdryer has a resistance of 46 Ω and a current of 5 A flows through it when in use. What is the voltage
across the hairdryer? (This is the mains voltage in the UK)
3/ What is the voltage across a lamp of resistance 4 Ω if a current of 2.5 A flows through it?
Please help :)
3/ What is the voltage across a lamp of resistance 4 Ω if a current of 2.5 A flows through it?
Please help :)
1 answer:
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Answer:
Kinetic energy is 1425.11 J.
Explanation:
Given:
Mass of the wrench is,
Height of fall is,
Force of resistance is,
Now, the total energy at the top is equal to the potential energy of the wrench at the top since the kinetic energy at the top is 0.
Now, potential energy at the top is given as:
Now, the potential energy at the top is converted to kinetic energy at the bottom and some energy is wasted in overcoming the resistance force by air.
Potential Energy = Kinetic energy + Energy to overcome resistance.
⇒ Kinetic energy = Potential Energy - Energy to overcome resistance.
Energy to overcome resistance force is the work done by the wrench against the resistance force and is given as:
Therefore, Kinetic energy at the bottom is given as:
Hence, the kinetic energy of the wrench be when it hits the water is 1425.11 J.