When you heat a certain substance with a difference of temperature

the heat (energy) you must give to it is

where

is the specific heat of that substance (given in J/(g*Celsius))
In this case

Observation: the specific heat of a substance is given in J/(g*Celsius) or J/(g*Kelvin) because on the temperature scale a
difference of 1 degree Celsius = 1 degree Kelvin
Answer:
A) 21.2 kg.m/s at 39.5 degrees from the x-axis
Explanation:
Mass of the smaller piece = 200g = 200/1000 = 0.2 kg
Mass of the bigger piece = 300g = 300/1000 = 0.3 kg
Velocity of the small piece = 82 m/s
Velocity of the bigger piece = 45 m/s
Final momentum of smaller piece = 0.2 × 82 = 16.4 kg.m/s
Final momentum of bigger piece = 0.3 × 45 = 13.5 kg.m/s
since they acted at 90oc to each other (x and y axis) and also momentum is vector quantity; then we can use Pythagoras theorems
Resultant momentum² = 16.4² + 13.5² = 451.21
Resultant momentum = √451.21 = 21.2 kg.m/s at angle 39.5 degrees to the x-axis ( tan^-1 (13.5 / 16.4)
Question: What is the frequency of a wave that has a wave speed of 120 m/s and a wavelength of 0.40 m?
Answer: The equation that relates frequency of a wave to a waves speed and wavelength is Speed of Wave= Frequency X Wavelength. Since you are given speed and wavelength, you plug those two known numbers into the equation, 120= Frequency X 0.40. You then divide 120 by .4 to get your frequency of 300.
Explanation: this might help for
Answer: n=4
Explanation:
We have the following expression for the volume flow rate
of a hypodermic needle:
(1)
Where the dimensions of each one is:
Volume flow rate 
Radius of the needle 
Length of the needle 
Pressures at opposite ends of the needle
and 
Viscosity of the liquid 
We need to find the value of
whicha has no dimensions, and in order to do this, we have to rewritte (1) with its dimensions:
(2)
We need the right side of the equation to be equal to the left side of the equation (in dimensions):
(3)
(4)
As we can see
must be 4 if we want the exponent to be 3:
(5)
Finally:
(6)