Earth's gravity attracts a person with a force of 120 lbs. The force with which the Earth is attracted towards the person is
120 lbs.
Which planets exhibit retrograde motion, that is, periodically appear to reverse their direction of motion across the sky?
All of the planets show retrograde motion.
After their rocket engines shut off, astronauts experience weightlessness in the orbiting Space Shuttle,
and they are accelerating because they are actually in free fall.
A rock that weighs 100 lb on Earth is taken to the Moon. As strange as it may seem, it is just as difficult to lift the 100 lb rock on the Moon as on the Earth. This is because
Nonsense! The rock is more easily lifted on the Moon.
For reasons known only to them, a group of extraterrestrials offers you your choice of three gold ingots. One weighs 10 lb on Earth, the second weighs 10 lb on Jupiter, and the third weighs 10 lb on the Moon. To get the most gold, you should choose the in
the Moon.
An object weighs 20 newtons on Earth. What is its approximate mass?
2 kg.
An object undergoes uniform circular motion. Which pair of vectors is perpendicular?
Its centripetal acceleration and velocity vectors.
Which of the following is NOT a vector?
A. Acceleration
B. Weight
C. Mass
D. Velocity
E. All of these choices are correct
C. Mass
A banked curve in a roadway is designed for a speed of 35 mph. During an ice storm cars should be able to safely negotiate this curve at 35 mph, because at this speed
the necessary centripetal force is supplied entirely by the normal force from the road.
The mass of an apple on the Earth is 0.2 kg. On the Moon, the mass of the same apple would be
0.2 kg.
Arnold can bench press 315 pounds in his gym in California. That is exactly six big 45-pound weights and the 45-pound bar. He can lift all that one time, but he cannot lift 325 pounds even once. At the NASA gym on the Moon, Arnold would
be able to bench press more than 6 plates.
Six identical blocks of steel, each with mass 10.0 kg, are taken to the Moon. On the Moon, their combined mass is
60.0 kg.
Two cars that have the same mass are moving around a circular track at the same constant speed. The track is perfectly level. If car 1 is at the inner edge of the track and car 2 is at the outer edge, then
the frictional force on car 1 is greater than the frictional force on car 2.
A cyclist races around a circular track at the constant speed of 20 m/s. The radius of the track is 50 m. The acceleration of the cyclist is
8 m/s^2, toward the center of the track.
A man weighs 600 N while on the surface of Earth. If he is transported to the planet Mythos, which has the same mass as Earth but a radius that is five times larger than Earth's, his weight would be
24 N.
The orbet of Comet UX209 about the Sun is not a circle but it orbits once every 365 days, just as Earth does. UX209 is closer to the Sun in April than it is in October. Thus, the speed of UX209 as it moves along its orbit is
greater in April than in October.
An asteroid moving around the Sun happens to experience only negligible forces from other objects in the solar system. The path of this asteroid will be
an ellipse.
A car travels around a curve with constant speed. The correct statement from the following is
the car has an acceleration directed inward toward the center of the curve.
A ball is whirled on the end of a string in a horizontal circle at constant speed. Suddenly, the string breaks. Immediately after the string breaks, the ball will
have a horizontal velocity that is tangential to the circle.
Car A travels with a speed v around curve number one, which has a radius r. Car B travels with speed 2v around curve number two, which has a radius 2r. The acceleration will be
greater for car B.
If a ball at the end of a string is whirled in a vertical circle at constant speed, the tension will be
greatest at the lowest point in the motion.
The first scientist to determine that the orbits of the planets are ellipses was
Kepler.
The heliocentric model of the solar system gained preference over the early Greek epicycle model because
the heliocentric model was simpler.
According to Newton's Law of Gravitation, if the distance between two bodies is doubled the attractive force between them becomes
one quarter as large.
The Sun and Moon both have an effect on the tides. Which one has the larger effect, and why?
The Moon, because its force differs more between the surface and center of the Earth.
Suppose a planet has a mass of 10 times that of the Earth and a radius that is 100 times that of the Earth. The acceleration of gravity on the surface of the planet, expressed in units of the Earth's acceleration of gravity, g, is
g/1000.
Suppose an artificial satellite has been put into circular orbit about the Earth, at a distance from the center of the Earth equal to 1/4 the distance from the Earth's center to the Moon's center. In terms of the Moon's period Tm, what will be the period
Tm/16
On a two-lane highway (not divided), a car headed north experiences a centripetal acceleration directed toward the east. Simultaneously, a truck passes the car, headed south in the other lane. The direction of the centripetal acceleration of the truck is
east.
What are the units for the constant G used in Newton's law of universal gravitation?
(N m^2)/kg^2
If you are ever fortunate enough to experience a total eclipse of the Sun, you can be sure that it will happen when the Moon is
in the "New Moon" phase.
In Vienna, there is a Ferris wheel designed so that the passengers ride in a standing position. If one of the passengers were standing on a bathroom scale, the scale would read lowest at
the highest point in the ride.
During a New Moon, when the Sun and the Moon are on the same side of the Earth, the people who live next to the ocean will see about how many high tides per day?
two
Two artificial satellites are in circular orbits about the Earth. Which of the two will be moving more slowly in its orbit?
The higher one.
A full moon is just now rising. Approximately what time of day is it?
6:00 PM
If a curve is banked to accommodate cars traveling at 15 m/s what will happen during an ice storm (no friction with the road) to a car moving at a slower speed?
It will gradually slide down the bank.
In his models of the motions of the planets, Copernicus
continued to use epicycles to explain planetary motion.
In order to move in a perfectly circular path, the net force on an object must
always change direction but not magnitude.
Two stars of different masses move directly toward each other. As the distance between the stars decreases, the speed of the stars
increases for both.
If you took a Ferris wheel ride in space while sitting on a bathroom scale, your weight
would be constant and larger than zero for the entire ride.
Two cyclists of different mass take a turn on a level road. They follow the same path and are moving the same constant speed for the turn. What is a correct statement about the two cyclists?
The acceleration is not zero but is the same for both.
If Newton's law of universal gravitation turned out to be Gm1m2/r rather than Gm1m2/r^2, tides on Earth
would still occur because each side of the Earth would feel a different gravitational force from the Moon.
If two bicyclists move around a circular track of radius 100 m, at the same speed 10 m/s, but in opposite directions, then
they have equal size accelerations, 1 m/s^2
When you spin your little brother, who is in first grade, on a "helicopter" ride, the acceleration of the first grader is
inward toward you, and you must pull the first grader inward.
When you swing your partner at an old-time square dance, you lock elbows and your partner is also swinging you. As a result, you both move in a circle. For this reason,
your partner and you mutually and simultaneously pull each other.
Kepler's three laws of planetary motion were useful but not considered fully explained until
Newton introduced the law of universal gravitation for astronomical and terrestrial objects.
Acceleration due to gravity is 9.8 m/s^2 on the surface of Earth, and at orbits 200 miles above the surface of Earth, where the space shuttle orbits, the acceleration is
less than 9.8 m/s^2.
The ______ of a body decreases as it is moved away from the surface of the Earth.
weight
A body moving in a circular path at constant speed exhibits acceleration because its __________ is changing.
velocity
A car can move at constant speed on a level curve on a highway as long as the force of _______ between the pavement and tires is sufficient to provide the necessary centripetal force.
friction
A car could move at a constant speed on an icy curve which is banked for ______ (all, one, no) speed(s) of the car.
one
A person weighing 500 N rides on a Ferris wheel sitting on a bathroom scale. At the highest point the scale reads 200 N while the person continues to move in a circular path. The centripetal force on the person at this point is ______ N.
300
To explain the retrograde motion of planets, Ptolemy introduced the concept of
epicycles.
If a person sits on a bathroom scale while riding on a Ferris wheel, the reading on the scale will be lowest while passing through the ______ point (indicate a point in the path).
highest
Two satellites are projected into circular orbits about the Earth. The one closer to the Earth has a period of 90 minutes. The one further away will have a period which is ___________ (longer, shorter, or same as) compared to 90 minutes.
longer
If the Earth rotated more slowly so that the length of a day was longer, the radius of a communications satellite in synchronous orbit would be
larger.
A lunar eclipse can only happen when the moon is __________ (what moon phase).
full
Stricly speaking, Newton's law of universal gravitation, F = Gm1m2/r^2, is valid only if the masses are either point masses or
perfect (uniform) spheres.