Answer:

Explanation:
The interaction of the piece of copper and water means that the first one need to transfer heat in order to reach a thermal equilibrium with water. Then:

After a quick substitution, the expanded expression is:



The final temperature of the system is:

Answer:
<em>The average speed of the train is 45 km/h</em>
Explanation:
<u>Speed</u>
It's defined as the distance (d) per unit of time (t) traveled by an object. The formula is:

Let's call x the total distance covered by the train. It covered d1=1/3x with a speed of v1=25 km/h. The time taken is calculated solving for t:



Now the rest of the distance:
d2 = x - 1/3x = 2/3x
Was covered at v2=75 km/h. Thus the time taken is:



The total time is:



Simplifying:

The average speed is the total distance divided by the total time:

Simplifying:

The average speed of the train is 45 km/h
Answer:
1000 mph
Explanation:
P = Perimeter = 24000 mi
r = Radius of the equator
t = Time taken to complete one rotation = 24 h
Perimeter of a circle is given by

Angular speed is given by

Velocity if given by

The person would be going at a speed of 1000 mph
Answer:
196000 N
Explanation:
The following data were obtained from the question:
Height (h) = 10 m
Area (A) = 2 m²
Force (F) =.?
Next, we shall determine the pressure in the tank.
This can be obtained as follow:
P = dgh
Where
P is the pressure.
d is the density of the liquid.
g is acceleration due to gravity
h is the height.
Height (h) = 10 m
Density (d) of water = 1000 kg/m³
Acceleration due to gravity (g) = 9.8 m/s²
Pressure (P) =...?
P = dgh
P = 1000 × 9.8 × 10
P = 98000 N/m²
Therefore, the pressure acting on the tank is 98000 N/m²
Finally, we shall determine the force of gravity acting on the column of water as follow:
Area (A) = 2 m²
Pressure (P) = 98000 N/m²
Force (F) =.?
Pressure (P) = Force (F) /Area (A)
P = F /A
98000 = F/ 2
Cross multiply
F = 98000 × 2
F = 196000 N
Therefore, the force of gravity acting on the column of water is 196000 N