August 29, 2007 PHY2053 Warm Up Quiz (Not graded)

August 29, 2007
Warm Up Quiz (Not graded)
Chapter 1 & Appendix A
1. You are allowed to use a formula sheet with its sides 11in. and 8.5 in. What’s the
area of the sheet in square centimeters (cm²)?
11in×8.5in=93.5 in²
93.5 in²×(2.54cm/1in)²=603.2 cm²
2. Two buildings are located 100m apart. An observer is on the top of the shorter
building. The observer notices that the top of the taller building is in the direction 30º
above the horizontal and the bottom of the building is in the direction 45° below the
horizontal. What is the height of the taller building?
The height of the shorter building=100tan45º=100m
The difference of the heights between the two buildings=100tan30º=57.7m
The height of the taller building=100+57.7=157.7m
3. Solve 3x²-2x-8=0 in two ways:
1) Factoring the equation
2) Using the formula
1) 3x²-2x-8=1×3x²+(1×4-3×2)+2×4=(x-2)(3x+4)=0 x=2, -4/3
2) x=(2±√(2²+4×3×8))/2×3=(2±10)/6 x=2, -4/3
4. Newton’s law of universal gravitation is given by F=GMm/r². What’s the dimension of
[G]= [F][r²]/([M][m]), where F is force, M and m are masses and r is distance.
Thus [G]=(MLTˉ²)(L²)/M²=L³/(MT²)