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A hairdryer transfers 36,000J in one minute, what is the power rating of the hairdryer?


Calculate the work done where 99W is used over 360s

Calculate the efficiency of a kettle which takes 100J and transfers it into 55J



Calculate work done when an object has an applied force of 5N and moves a distance of 4m

An electric fire needs 4 kW. It is switched on for 4 hours. If each kWh costs 2p, how much does it cost to run the fire?

Please help me quick I only have tomorrow left

Thank you ​

Respuesta :

olayemiolakunle65

Answer:

1. 600 watts

2. 35640 J

3. 55%

4. 20 J

5. The cost of running the fire is 8p.

Step-by-step explanation:

1. Energy = 36 000 J , t = 1 minute = 60 seconds

Power = [tex]\frac{energy}{time}[/tex]

           = [tex]\frac{36000}{60}[/tex]

          = 600 watts

2. Power = [tex]\frac{work done}{time}[/tex]

⇒ work done = Power × time

                      = 99 × 360

                      = 35640 J

3. Efficiency = (Output / Input) × 100

                    = [tex]\frac{55}{100}[/tex] × 100

                    = 55%

4. Work done = Force × distance

                      = 5 × 4

                      = 20 J

5. Given that 1 KWh cost 2p, Power = 4 KW and time = 4 hours.

  Power = [tex]\frac{energy}{time}[/tex]

Energy = Power × time

            = 4 × 4

           = 16 KWh

The cost of running the fire = [tex]\frac{16}{2}[/tex]

                = 8p

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