Physics midterm first half

an object moves 20 m east and 30 seconds and then returns to its starting point taking an additional 50 seconds. if west is chosen as a positive direction, then what sign is associated with the average velocity of the object

0 (no sign)

a earth satellite is orbiting at a distance from the earth's surface equal to two earth radii. at this location, the acceleration due to gravity is what factor times the value of g at the earth's surface?

1/9

a room has 110 ft^2 of floor space. what is the approximate volume of the room

10^3 ft^3

an object moves at a constant velocity of 12 m/s to the southwest for an interval of 20 s. halfway through this interval what is the magnitude of its instantaneous velocity

12 m/s

in which of the following cases is the displacement magnitude half the distance traveled

15 steps East followed by five steps west

an object initially moving in the negative X direction is subjected to a change in velocity in the negative Y direction. if the resulting velocity vector is drawn from the origin into which quadrant does this vector point?

3rd

an observation satellite for mapping purposes is placed in a low earth orbit. in order to see the whole surface of the earth, which would be the preferred orbit

A polar orbit

it is late and Carlos is sliding down the rope from his third floor window to meet his friend juan. as he slides down the rope faster and faster he becomes frightened and grabs harder on the rope, increasing the tension in the rope. as soon as the upward tension in the rope becomes equal to his weight

Carlos will continue down at a constant velocity

an x-t graph is drawn for the ball moving in One Direction. The graph starts at the origin and at T equal six seconds the velocity of the ball is zero. we can be positive that T equals six seconds

The ball has stopped

of the known planets in our solar system, the innermost is mercury. when compared to the other planets in the system, mercury has:

The greatest centripetal acceleration

which of the following expresses the principle which was Initially stated by Galileo and was later incorporated into newtons laws of motion

The natural condition for a moving object is to remain in motion

if we know an object is moving at a constant velocity we may assume

The net force acting on an object zero

assume that a reference frame is moving with the person indicated in each of the following situations. in which case is the reference frame non-inertial?

The person is skydiving and it's freefalling not yet having opened her parachute

The slope of the acceleration time curve represents

The rate of change of acceleration

A physics student is writing on a train traveling north. having read about inertia the student performs an experiment with the golf ball he reaches over the aisle and drops the ball from rest instead of hitting the floor directly below the student's hand it hits to the north, forward of that position. which of the following might be the cause for this to happen

The train is slowing down

a strobe photograph shows equally spaced images of a car moving along a straight road if the time intervals between images is constant. which of the following cannot be positive

The train is slowing down

a stone is thrown downward from a cliff. Take "up" to be the positive direction in which of the following statements is true about the stone

The velocity is negative, the acceleration is negative, and the speed is positive

a v-t graph is drawn for a ball moving in One Direction. the graph starts at the origin and at t=6 seconds the acceleration of the ball is zero. we know that at t=6

The velocity of the ball is not changing

Which following is dimensionally consistent with an expression yielding a value for velocity

a/t

baseball is thrown by a centerfielder (from shoulder level) to home plate where is caught (on the fly at shoulder level) by the catcher. at which point is the magnitude of the acceleration at a minimum at which point is the magnitude of the acceleration at a minimum. note: air resistance is negligible

acceleration is constant during the entire trajectory

when we added displacement vector to another displacement vector the result is

another displacement

Jeff throws a ball straight up, for which situation is the vertical velocity zero

at the top

A baseball catcher throws a ball vertically upward and catches it in the same spot when it returns to his mitt, at what point in the balls path does experience zero velocity and nonzero acceleration at the same time

at the top of its trajectory

A string is attached to the ceiling, at the bottom of the string, a rope of the same length as the string is attached the rope. in the rope-string system which of the following is the position of the greatest tension? Assume the rope has more mass per unit length in the string

at the top of the string

baseball is thrown by the centerfielder(from shoulder level) to home plate where is caught (on the fly at equal shoulder level) by the catcher. at what point is the ball's speed at a minimum? note: Air resistance is negligible

at the top of the trajectory

on a position-time graph, the slope of the straight line joining two points on the plotted curves are separated in time by the internal change in t, is which of the following quantities?

average velocity

if we know that a nonzero net forces acting on an object, which of the following must we assume regarding in objects condition? the object is

being accelerated

Two objects of different masses are released simultaneously from the top of a 20 m tower and fall to the ground. if air resistance is is negligible which statement best applies

both objects hit the ground at the same time

At what location does an artificial earth satellite in an elliptical orbit have its lowest speed

farthest from the sun

Which of the following best describes the property of the period of orbital revolution for an Earth satellite

greater when the orbital radius is larger

A wheel is rotated about a horizontal axle at a constant angular rate. next it is rotated in the opposite direction with the same angular rate. The acceleration a point on the top of the wheel in the second case as compared to the acceleration in the first case:

is in the same directions

in one-dimensional motion where the direction is indicated by a plus or minus sign, The average velocity of an object has which of the following properties

it can be positive, negative, or zero

in one dimensional motion the average speed of an object that moves from one place to another and then back to its original place has which of the following properties

it is positive

A car is going around a race track at a constant speed. The curves around the track have different radii. in which turn is the magnitude of the cars acceleration the greatest

it is the greatest in the turn with the smallest radius

for a point on a spinning disk in uniform circular motion, which of the following is not a constant?

it's centripetal acceleration

The earths orbit is closest to the sun in January ann farthest from the sun in July. What is the earth moving the slowest in orbit

july

and artificial earth satellite an elliptical orbit has its greatest centripetal acceleration when it is at what location

nearest the earth

according to Kepler's law, Haleys comet circles the sun in an elliptical path with the sun at one focus of the eclipse. what is that Kepler's law indicates is at the other focus of the eclipse

nothing

baseball is moving in the air along the customary parabola. ignoring air drag where is the force on the baseball zero

nowhere

The value of an objects acceleration may be characterized in equivalent words by which of the following

rate of change of velocity

Changing a positive direction in a reference frame to the opposite direction does not change the side of which of the following quantities

speed

which of the following is not a vector quantity

temperature

about moves through the water in a river at a speed of 8 m/s relative to the water. The boat makes the trip downstream and then makes the return upstream to the original starting place. which trip takes less time?

the downstream trip

two objects are in circular orbits of different radii around the sun. which object has the lowest orbital speed

the one farthest from the sun

what is (are) the location(s) of the low tide(s) on the earth caused by the gravitation of the moon? give the location(s) relative to the line through the Earth's and Moon's centers, line EM

the points on the Earth's surface perpendicular to EM at the Earths center

The statement by Newton that for every action there is an opposite but equal reaction is regarded as which of the laws of motion

third

when it comes to tides, high and low, what is the usual situation in the ocean's coast?

two high tides and two low tides a day.

consider a point on a bicycle tire that is momentarily in contact with the ground as the bicycle rolls across the ground with constant speed. The direction for the acceleration for this point at that moment is

upward

which is not dimensionally correct

v= a/t

displacement is which of the following types of quantities

vector

in the terminology "a 500- N block" the "500- N" refers to the block's

weight

A change in physical quantity w, having initial value wi, and final value wf is given by which of the following

wf-wi

As the car moves forward on a level Road at a constant velocity the total force acting on the tires is

zero