How does the strength of an electromagnet depend on the current and the number of turns in the coil?

Question

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During a race, a runner runs at a speed of 6 m/s. 2 seconds later, she is running at a speed of 10 m/s. What is the runner’s acceleration?

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If you ride your bike at an average speed of 4 km/h and need to travel a total distance of 28 km, how long will it take you to reach your destination?

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A small dog is trained to jump straight up a distance of 1.2 m. How much kinetic energy does the 7.2-kg dog need to jump this high? (The acceleration due to gravity is 9.8 m/s2.) Show your work.

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As 390 g of hot milk cools in a mug, it transfers 30,000 J of heat to the environment. What is the temperature change of the milk? The specific heat of milk is 3.9 J/g•°C. Show your work.

anonymous · Answer

1.  A solenoid is a electromagnet. From $$B=\mu \times n \times i$$
     B-strength of magnetic field.
     u-permeability of the core.
     n-number of turns.
     i-current.
     You can see why 'B' depends on 'i' and 'n'.

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2. If the acceleration is constant , a=10-6/2 i.e $$2 m/s ^{2}$$

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3. The definition of avg.speed is total distance traveled divided by the total time taken.

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4. The kinetic energy is getting converted to potential energy.
     So, decrease in kinetic energy=increase in potential energy.$$1/2\times m \times v ^{2} = m \times g \times h$$
    Now mgh is your answer.

anonymous · Answer

$$Q=m \times c \times \Delta T$$
Q- heat exchanged.
m- mass.
c- specific heat.
delta(T)-change in temperature.