Homework 2
Due September 18th
1) Define the following terms (give formulas when appropriate, and units for parts b to e):
a.
Vector
b.
Velocity (you should explain how velocity is different from speed)
c.
Acceleration
d.
Force
e.
Mechanical Energy (also define any new terms you encounter)
2) What is the difference between an independent variable and a dependent variable? How
is this distinction important when conducting experiments? When graphing data, which
axis is typically used for the independent variable?
3) What is the difference between instantaneous speed and average speed? It is extremely
difficult to obtain an exact measurement of instantaneous speed; often, scientists get by
with approximate measurements of instantaneous speed. How can you obtain an
approximate measurement of instantaneous speed?
4) Soda is a solution consisting primarily of water, along with some other substances to
provide flavor, color, etc. Note that dissolving a substance in a liquid doesn’t change the
volume of the liquid significantly; you may check this claim by observing that a water
bottle never overflows when you drop a powdered flavor-enhancer into it. Consider a
very primitive 12 fl. oz. soda (ignore the effects of carbon dioxide), consisting only of
water and sugar. If the density of the soda is 1.2 g/cm3, what is the mass (in grams) of the
sugar in the solution?
The density of water is 1 g/cm3. The unit “fl. oz.” or “fluid ounce” is a unit of volume;
make sure to do the required unit conversion before performing the calculations.
5) Joules are units of energy. What is the formula for a Joule in terms of meters, kilograms,
and seconds? A Calorie is also a unit of energy. A certain hamburger contains 670
Calories of energy. How much energy is that in Joules?
Be careful—Calorie and calorie are two different units, they differ by a factor of 1000.
The unit Calorie (with a capital C) is 1000 times larger than the unit of calorie (with a
lowercase c). To avoid confusion, a Calorie is sometimes called a Food Calorie or a
Kilocalorie.
If you are having difficulty with unit conversion, you may find the following tutorial
helpful:
https://www.physics.uoguelph.ca/tutorials/units/Units1.htm