The core of a star must be at the temperature of 10,000,000 degrees Celsius for hydrogen fusion to begin.
As a liquid is cooled its molecules lose kinetic energy and their motion slows. When they've slowed to where intermolecular attractive forces exceed the collisional forces from random motion, then a phase transition from liquid to solid state takes place and the material freezes
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<span>In this problem, we need to solve for Bubba’s mass. To do this, we let A be the area of the raft and set the weight of the displaced fluid with the raft alone as ρwAd1g and ρwAd2g with the person on the raft, </span>where ρw is the density of water, d1 = 7cm, and d2= 8.4 cm. Set the weight of displaced fluid equal to the weight of the floating objects to eliminate A and ρw then solve for m.
<span>ρwAd1g = Mg</span>
ρw<span>Ad2g = (M + m) g</span>
<span>d2∕d1 = (M + m)/g</span>
m = [(d2<span>∕d1)-1] M = [(8.4 cm/7.0 cm) - 1] (600 kg) =120 kg</span>
This means that Bubba’s mass is 120 kg.
I) You walk barefoot on the hot street and it burns your toes.
The road is in direct contact with your skin. Thermal energy from the road will transfer to the bottom of your feet, then to the rest of your body. This is an example of conduction.
II) When you get into a car with hot black leather in the middle of the summer and your skin starts to get burned.
Just like in the previous example, the hot leather is in direct contact with your skin (I guess if you're going to drive naked). Thermal energy from the leather will transfe to your skin, then to the rest of your body. This is also conduction.
III) A flame heats the air inside a hot air balloon and the balloon rises.
The flame heats air directly at the bottom of the balloon. The warm air expands and becomes less dense. This will rise and let the unheated, denser air in the balloon fall down toward the flame. This is an example of the convection cycle.
IV) A boy sits to the side of a campfire. He is 10 feet away, but still feels warm.
The campfire heats air directly nearby. The warm air expands and moves away from the fire in all directions, leaving behind unheated, denser air to be heated up. Some of the warm air reaches the boy. This is another example of convection.
The answer is A) 1 and 2.
