Why can’t we see through walls?
We see the photons emitted by electron energy level jumps, not physical objects.
What element is the most common in air?
Nitrogen, it’s about 70%.
What are the base SI units of acceleration?
m/s^2
Traveling at 22m/s, how far does a vehicle go in 20s?
440 m
Can acceleration be negative?
yes
Do you feel your own weight?
No, you feel the force of the world pushing upwards on your feet.
Which freezes faster, hot water or cold water?
Sometimes hot water, but that’s not always true.
What is the mass of Earth (just get it within 10x)?
5.972*10^24 kg
What is the velocity of a vehicle that travels 300m in 15s (give the answer in m/s)?
20 m/s
What's the acceleration due to gravity on Earth's surface?
g=9.81 m/s^2
How far are you from Earth right now?
One radius of Earth, 6378km.
How heavy is the Pacific ocean?
Pacific Ocean covers 28% of the planet’s surface
Planet’s radius is 6378km and the surface area is .
Average depth is 4280m. Use that to find V if it’s a cylinder.
Multiply volume by density of water and gravity.
Which number is bigger?
10^10 * 10^10 or (10^5)^5
(10^5)^5
8.81s
If a rocket accelerates at 30 m/s^2 for 5 minutes, what is it's final velocity?
9000 m/s
Where does sound travel faster, in the air or in water?
It’s much faster in water. In air , in water
.
Why are sunsets red?
Earth’s atmosphere blocks more blue light than right light, so if the light passes through more atmosphere, it looks redder.
What are the base SI units of energy?
kg*m^2/s^2
What's the average vertical velocity of a projectile?
0 m/s
How long does it take to reach terminal velocity, 52.7 m/s, if you're falling at g=9.81m/s^2?
5.37s
Are the atoms in your feet touching the atoms in the floor?
No, they’re separated by about 0.5nm due to electric repulsion.
Why do bubbles pop?
The internal pressure inside of the bubble is higher than the outside air. If there is a small hole in the thin film, the air escapes.
What is the fastest velocity any land vehicle has ever traveled (the land speed record) in units of m/s?
Guess within 10x
341 m/s (762 kmph)
Find the average velocity of an object that travels at 20m/s for 10s, stops for 1 minute, then travels in the same direction at 10m/s for another 10s.
3.75 m/s
Find the average acceleration of an object that accelerates at 10m/s^2 for 10s, then decelerates at 5 m/s^2 for 5s, before accelerating at 10m/s^2 for another 10s.
7 m/s^2