I think it’s going to be the 2nd one
Answer: The ice and shel are at the same temperature.
Explanation: Conduction happens when you have two objects at different temperatures touching each other, in this case, the temperature flows from the hot object to the cold one, until the equilibrium is reached (this means that both objects are at the same temperature). So, in order to conduction to happen, we need a difference in temperature and direct contact. So there are two options of the given that can be the answer: "There is no direct contact" In the sentence says that "the ice is placed on the freezer shelf", so we have direct contact between both objects. "The ice and shelf are at the same temperature" Here both objects are inside of the freezer, so we can expect that both of them are at the same temperature, hence, there is no conduction.
Answer:
4m/s
Explanation:
The motion is in downward direction, and the boat is moving with constant velocity, the position of the boat horizontally is 12m before the key fall.
The height difference "h"= ( y- y°)= 45 m
We can determine the needed time the key requires to reach the water using the expression from Newton's law
h= v(o) + 1/2 at^2
g= acceleration due to gravity= 9.8m/s^2
h= v(o) + 1/2 gt^2 -------------------------eqn*)
V(o)= 0 for the key= initial velocity
h= height that the key falls= 45m
If we substitute the above values into eqn(*) we have
We can make t^2 subject of the formula since v(0)= 0
t^2= h/(1/2 g)
= 45/(1/2× 9.8)
t^2= 45/4.9=9.18
t= √9.18
t=3.03 secs
Since the boat was moving with constant velocity,
Then Velocity= distance/ time
= 12/3.03
Velocity= 4m/s
Hence, the speed of the boat is 4m/s
Answer:
They investigated Hooke's law.
Explanation:
