Physics & Technology for Future Presidents--Chapter 3

At high velocities, most of the fuel used in an automobile is used to overcome

At high velocities, most of the fuel used in an automobile is used to overcome

air resistance

Balloons rise until

the surrounding air becomes too thin (not dense)

At an altitude of 200 km, the downward force of gravity on an Earth satellite is

a little bit weaker

Airplanes fly (maintain their altitude) by

pushing air downward

Rockets fly by

pushing fuel downward

The storm surge in a hurricane comes from

the low pressure

When an astronaut in space sneezes, his head is snapped back with higher velocity than on Earth, because

Wrong! His head is not snapped back with higher velocity

A rail gun

doesn't really accelerate things

The Sun would be a black hole if it were squeezed into a radius of

2 miles

The method that would take the least energy to get something to space is

lifting it by elevator (if the elevator existed)

If an artificial satellite orbited the Earth at 240,000 miles (the distance to the Moon), it would orbit the Earth in a period of

1 month

The time it takes a geosynchronous satellite to orbit the Earth is

1 day

The force of gravity between two people standing next to each other is

too small to measure

You can see where the tropopause is by

looking at the tops of thunderstorms

If satellites fly too low, they will crash because

of stronger gravity

Ice-skaters spin faster by pulling in their arms. This illustrates that

angular momentum is conserved

Someone firing a rifle is pushed back by the rifle. This illustrates that

momentum is conserved

A problem with rail guns is that

the high accelerations can cause damage

The maximum acceleration of the space shuttle is about

3 g's

The lowest practical altitude for a satellite orbiting the Earth is about

200 km

For very high velocities, the best kind of rocket to use is

ion rocket

The altitude of a geosynchronous satellite is closest to

22,000 miles

Skyhook, if built, is

a way to get into space using less energy

If you fall for one second, your speed will be approximately

22 mph

Artificial gravity can be created in a spaceship by

accelerating the ship

Orbital velocity is about

5 miles per sec

The Sun is mostly hydrogen, yet the Earth has very little hydrogen gas. That's because:

it escaped to space

The orbit of GPS is

MEO

A geosynchronous satellite orbits the Earth

once every 24 hours

A typical spy satellite can continuously observe a location on the ground for about

one minute

Compared to the weight of the payload, the fuel used in a rocket to orbit typically weighs

over 20 times more

A cubic meter balloon can lift

about 2 pounds

Spy satellites usually fly at

LEO