M1 v1 = (m1 + m2)v2.
All of the exponents should be lowered to the bottom right of the letters.
Answer : The heat change of the cold water in Joules is, 
Explanation :
First we have to calculate the mass of cold water.
As we know that the density of water is 1 g/mL. The volume of cold water is 45 mL.
Now we have to calculate the heat change of cold water.
Formula used :
where,
Q = heat change of cold water = ?
m = mass of cold water = 45 g
c = specific heat of water = 
= initial temperature of cold water = 
= final temperature = 
Now put all the given value in the above formula, we get:
Therefore, the heat change of cold water is
120 km/3 hours. 40/1=?/3 1x3=3 hours so 40x3=120 km
First electromagnet
Explanation:
The first electromagnet is the strongest and it is stronger than the given electromagnet above.
An electromagnet is a temporary magnet made by passing current through a wire wounded round an iron core or metallic core.
- When current is passed through, the metal becomes magnetic.
- The strength of the electromagnet depends on the number of coil round the metal core and also the intensity of current passed through it.
- The higher the number of coils wounded round the metal core, the stronger the electromagnet that will be produced.
- Also, the higher the intensity of electricity passed through the wire, the stronger it is.
learn more:
Electromagnet brainly.com/question/2191993
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