CH 10

What exactly is a projectile

Any object that moves through the air or through space under the influence of gravity.

We talk of 11.2 km/s as the escape speed from Earth. Is it possible to escape from earth at half this speed

At one quarter of this speed? If so how?It is possible to escape Earth at any sustained speed more than zero, given enough time.

A stone is thrown upward at an angle. What happens to the horizontal component of its velocity as it rises, As it falls

Rising or falling it does not change.

How much time is taken for a complete revolution of a satellite in close orbit about the Earth

90 minutes

A projectile falls beneath the straight-line path it would follow if there were no gravity. How many meters does it fall below this line if it has been traveling for 1 s, For 2 s

After one second it would be 5m and after 2 seconds it would be 20 m. Because of 5t^2.

A projectile is launched upward at an angle of 75˚ from the horizontal and strikes the ground a certain distance downrange. For what other angle of launch at the same speed would this projectile land just as far away

An angle of 15˚ would produce the same range, because the angels sum up to 90˚.

Why doesn't the force of gravity change the speed of a satellite in a circular orbit

Because gravity pulls straight downward with no component of force acting forward or backward, meaning there is no component of gravitational force in the direction of its motion.

Why must a horizontally moving object have a large speed to becomes an Earth satellite

Because it needs to be at a speed that the earth will have turned by the time it stops moving.

Why will a projectile that moves horizontally at 8 km/s follow a curve that matches the curvature of the Earth

Because of the fact that the curvature of Earth is that its surface drops a vertical distance of 5m for every 8km tangent to the surface.

Why is it important that the projectile in the previous question be above Earth's atmosphere

Because the atmospheric friction would burn the baseball to a crisp.

Why does the force of gravity change the speed of a satellite in an elliptical orbit

Because there is a component of the force in the direction of the satellite's motion. and gravitation slows it to a point where it no longer moves farther from Earth.

For orbits of greater altitude, is the period longer or shorter

For greater altitudes the period is longer.

How can a projectile fall around the Earth

If an object is projected fast enough to match the curvature of earth, then it will fall all the way around the Earth.

In Kepler's thinking, what was the direction of the force on a planet, In Newton's thinking, what was the direction of the force

In Kepler's thinking the direction of force on a planet was in its direction of motion. Newton believed the force was in the direction of the pull of gravity.

What did Kepler discover about the periods of planets and their distances from the Sun, Was this discovery aided by thinking of satellites as projectiles moving under the influence of the Sun?

Kepler discovered that the square of any planet's period is directly proportional to the cube of its average orbital radius. No, Kepler did no see that a satellite is simply a projectile under the influence of a gravitational force directed toward the body that the satellite orbits.

Why is kinetic energy a constant for a satellite in a circular orbit but not for a satellite in an elliptical orbit

Kinetic energy is constant for a satellite in a circular orbit because the distance between the satellite and the center of the attracting body does not change. However, in an elliptical orbit both speed and distance vary.

Do your answers to the previous question depend on the angle at which the projectile is launched

No, the falling distance beneath the line makes no difference whether or not the line is at an angle.

A projectile is launched vertically at 100 m/s. If air resistance can be neglected, at what speed will it return to its initial level

The projectile would return at the same speed of 100 m/s.

Is the sum of a kinetic and potential energies a constant for satellites in circular orbits, in elliptical orbits, or in both

The sum of a kinetic and potential energies a constant for both circular and elliptical orbits.

Why does the vertical component of velocity for a projectile change with time, whereas the horizontal component of velocity doesn't

The vertical component changes because vertical motion is influenced by the gravitational force (which acts in the vertical direction). The horizontal component of velocity doesn't change because there is no component of gravitational force acting horizontally.

A stone is thrown upward at an angle. What happens to the vertical component of its velocity as it rises, As it falls

The vertical component of velocity decreases as the stone rises, and increases as it falls.

Who gathered the data that were used to show that the planets travel in elliptical paths around the Sun, Who discovered elliptical orbits, Who explained them

Tycho Brache gathered the data showing planets traveled in elliptical paths. Johannes Kepler discovered the fact that planets follow elliptical paths. Sir Isaac Newton explained this fact.