Astronomy chapter 5
A solar sail is a large sheet of light-reflecting plastic spread on an extremely low-mass framework and attached to a spacecraft. Sunlight exerts a force on the sail and moves the spacecraft. Suppose the spacecraft has a total mass of 100kg (including the sail) and sunlight exerts a total force of 2N on the sail. What will be the acceleration of the spacecraft?
0.02 m/s squared
What total force will cause an object with a mass of 2kg to gain 5 meters per second every second?
10 newtons
Suppose that you lift an object by exerting an upward force of 22 Newtons on it. If gravity exerts a force of 10 Newtons downward on the object, what is the total force on the object?
12 newtons
Suppose that you drop two objects from the same height at the same time. Both objects are heavy enough to be unaffected by air resistance. If one object is twice as heavy as the other, Galileo predicted that
both objects would hit the ground at the same time
The International Space Station (ISS) is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose that it is desired to raise it to a new circular orbit, farther from the surface by having a rocket give it one or more short boosts. Which of the following schemes will work?
increases its speed to 6 miles per second to put it on a rising path & give it another speed boost when its distance from the Earth stops increasing
The gravitational attraction of the Earth for other objects...
is smaller for the objects farther from Earth, but never vanishes entirely
An artificial satellite such as the International Space Station stays up because
it falls below a straight line path in exactly the same way that the curved surface of the Earth does
Aristotle said that the amount of force on a moving earthly object determines its
speed
Compare the magnitude of the acceleration of Earth's Moon to the acceleration of falling objects on the surface of the Earth.
the Moon's acceleration is smaller
The recoil or 'kick' of a gun that is firing a bullet is a force exerted on the gun by
the bullet
According to Galileo, a thrown spear keeps moving after it has left the spear thrower's hand because
the force of friction with the air is not enough to stop the spear
If you are told that an object that weighs 20 Newtons is raised a distance of 10 meters, you know that...
the force of gravity on the object is 20 newtons
A horse is pulling a cart along a road. Which of the following pairs of forces is an action-reaction pair?
the force of the horse on the road and the force of the road on the horse
Suppose that an object with a mass of one kilogram and an object with a mass of two kilograms are both in free fall near the Earth's surface. As compared to the one kilogram object, the two kilogram object accelerates
the same because gravity pulls on it more strongly and has more inertia
A planet that is following Kepler's Laws, accelerates
toward the sun
If an object is moving at constant speed in a straight line, its acceleration is
zero