The electric magnet (Electromagnetic) is temporary because you can turn it on and off. When it's power source is gone, the magnet becomes useless. Usually it's power source is a battery, but it could be solar with a switch. Hope this helps. Please give me brainliest is this helps you.
D. <span>Johannes Kepler argued that Earth was the center of the universe.
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Answer:</h2>
He saves 13.2 minutes
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Explanation:</h2>
Hey! The question is incomplete, but it can be found on the internet. The question is:
How many minutes did he save?
Let's call:
We know that the 135 miles are on the interstate highway where the speed limit is 65 mph. From this, we can calculate the time it takes to drive on this highway. Assuming Richard maintains constant the speed:
Today he is running late and decides to take his chances by driving at 73 mph, so the new time it takes to take the trip is:
So he saves the time 
:
In minutes:
The heat transferred by room heater to the room is an example of convection heat flow.
Answer: Option D
<u>Explanation:</u>
It is known that heat or thermal energy generally flows from high temperature to low temperature. Heat can be transferred in four ways. They are conduction, convection, radiation and electro-magnetic waves. So, in the present case, if we are turning on the heater highers the temperature of the room, we need to use room heaters. And generally room heaters utilize convection technology to flow the heat energy.
In convection mode of heat flow, the heat energy generated at the source i.e., in the coils of the room heater is made to flow away from the source using the fan or radiator kind of thing. So, this process of transfer of heat energy from the point of generation by making the heat flow or rise is termed as convection. And thus, convection is the best example which is used in room heater.
Well, if there were no air resistance, then a helicopter couldn't fly. But let's do the physics and the Math anyway:
The way gravity works, the speed of a falling object increases at the rate of 9.8 m/s every second.
So, after falling for 12 seconds, its speed is (12 x 9.8) = <em>117.6 m/s </em>.
