3. A woman drove her car from home to her daughter's school. The odometre on her dashboard says she travelled 4.5 km to do this.
1 answer:
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Answer:
Explanation:
Magnetic field near current carrying wire
=
i is current , r is distance from wire
B = 10⁻⁷ x
force on second wire per unit length
B I L , I is current in second wire , L is length of wire
= 10⁻⁷ x x 33 x 1
= 3234 x
This should balance weight of second wire per unit length
3234 x = .075
r = x 10⁻⁷
= .0043 m
= .43 cm .
Answer:
80%
Explanation:
Efficiency = Power output / Power input × 100 %
To calculate efficiency we need to find power output of electric pump.
We can use,
Work done = Energy change
Work done per second = Energy change per second
Work done per second = Power
Therefore, Power = Energy change per second
= Change in potential energy of water per second
=mgh / t
= 200× 10×6 / 10
= 1200 W = 1.2 kW
Now use the first equation to find efficiency,
Efficiency = × 100%
= 80 %