The relevant equation to use here is:
y = v0 t + 0.5 g t^2
where y is the vertical distance, v0 is initial velocity =
0, t is time, g = 9.8 m/s^2
y = 0 + 0.5 * 9.8 * 3^2
<span>y = 44.1 meters</span>
False. First Law of Newton states that object tends to be at rest until an external force is applied and vice-versa.
Answer:
Photons strike the CD 
Explanation:
First of all, it is necessary to calculate the energy produced by a semiconductor laser for 69 minutes:


Next, it is possible to calculate the number of photons striking the CD surface during this time:

long in CD
light velocity
Solve to n'


Answer:
The equivalent resistance of the parallel circuit would be 20 Ω
Explanation:
To calculate the resistance of resistors connected in parallel, the formula to be used is
1/R = 1/R₁ + R₂ + R₃ + R₄...
1/R = 1/120 + 1/60 + 1/40
1/R = (1 + 2 + 3)/120
1/R = 6/120
1/R = 1/20 Ω
This can be rewritten or cross-multiplied to be
R × 1 = 20 × 1
R = 20 Ω
The equivalent resistance (R) would then be 20 Ω