physics unit one
What is the displacement ΔxΔxDeltax of the particle?What is the instantaneous acceleration aaa of the particle at t=45.0st=45.0s?
75m, -.20
Which of the following situations is impossible?
An object has constant non-zero velocity and changing acceleration.
A ball is thrown downward in the absence of air resistance. After it has been released, which statement(s) concerning its acceleration is correct? (There could be more than one correct choice.)
Its acceleration is constant.
Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?
Its acceleration is in the -x direction.
An object moves with a constant, negative acceleration, whats the graph shape
Parabolic, the parabola opens downward (inverse U-shaped)
If the velocity of an object is zero at one instant, what is true about the acceleration of that object? (There could be more than one correct choice.)
The acceleration could be positive.,The acceleration could be negative.The acceleration could be zero.
Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?
The acceleration is toward the east.
The figure shows a graph of the position x of two cars, C and D, as a function of time t. What must be true about the cars at point 10
The cars meet at time t = 10 s.Both cars have the same acceleration.
Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object.
The displacement is either less than or equal to the distance traveled.
What shape do we expect for a graph showing the position of a motorcycle versus time if the motorcycle is speeding up with a constant acceleration?
The position versus time graph is parabolic.
Suppose that you toss a rock upward so that it rises and then falls back to the earth. If the acceleration due to gravity is 9.8 m/sec2, what is the rock's acceleration at the instant that it reaches the top of its trajectory (where its velocity is momentarily zero)? Assume that air resistance is negligible.
The rock has a downward acceleration of 9.8 m/s2.
The motions of a car and a truck along a straight road are represented by the velocity-time graphs in the figure. The two vehicles are initially alongside each other at time t = 0
The truck will have travelled further than the car.
An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is
a horizontal straight line.
An object is moving with constant non-zero acceleration in the +x direction. The position versus time graph of this object is
a parabolic curve.
An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is
a straight line making an angle with the time axis.
An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is
a straight line making an angle with the time axis.
If the position versus time graph of an object is a horizontal line, the object is
at rest
An object moves along the x axis during four separate trials. Graphs of position versus time for each trial (with the same scales on each axis) are shown in the figure. During which trial or trials is the magnitude of the average velocity the largest?
curved line and straight line going down through x axis
A driver, traveling west, slows and stops at the stop sign.
curved line down to x axis
A driver, after stopping at the stop sign, travels east with a positive acceleration.
curved line on x axis positively growing
Over the nine-second interval shown, we can say that the speed of the particle
decreases then increases
Velocity differs from speed in that velocity indicates a particle's __________ of motion.
direction
Which of the following is a vector?
displacement
Speed differs from velocity in the same way that __________ differs from displacement.
distance
A child rides a pony on a circular track whose radius is 4.8 mm .
distance 15.1 displacement 9.6
If the velocity of an object is zero at some point, then its acceleration must also be zero at that point.
false
If the velocity of an object is zero, then that object cannot be accelerating.
false
Is the increase in speed of the hammer as it drops past window 1 greater than, less than, or equal to the increase in speed as it drops past window 2?
greater than the increase in speed as it drops past window 2///The hammer spends more time dropping past window 1.
Two objects are dropped from a bridge, an interval of 1.0 s apart. Air resistance is negligible. During the time that both objects continue to fall, their separation
increases
An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object
is increasing its velocity by 2.0 m/s every second
A vector has, by definition, both __________ and direction.
magnitude
If the velocity versus time graph of an object is a horizontal line, the object is
moving with zero acceleration
Which has the greater displacement, object 1, which moves from 5.0 mm to 7.0mm in 2.0 ss, or object 2, which moves from 15 mm to 16 mm in 25 ss?
object 1
The __________ of the particle at point A differ(s) as expressed in one coordinate system compared to the other, but the __________ from A to B is/are the same as expressed in both coordinate systems.
position, displacement
Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. Neglect air resistance. As time progresses, the difference in their speeds
remains constant
A driver ignores the stop sign and continues driving west at constant speed.
slanted line negatively growing through x axis
A driver ignores the stop sign and continues driving east at constant speed.
slanted line positive growing through x axis
A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t = 0 s. If we take upward as the positive direction, which of the graphs shown below best represents the acceleration of the stone as a function of time?
straight line under x axis
What does the intercept of a position-time graph represent?What does the initial slope represent?
the position xixi of the object at tt = 0//the velocity vivi of the object at tt = 0
Consider a car that travels between points A and B. The car's average speed can be greater than the magnitude of its average velocity, but the magnitude of its average velocity can never be greater than its average speed.
true
Consider a deer that runs from point A to point B. The distance the deer runs can be greater than the magnitude of its displacement, but the magnitude of the displacement can never be greater than the distance it runs.
true
Unlike speed, velocity is a __________ quantity.
vector
The slope of a position versus time graph gives
velocity
When is the average velocity of an object equal to the instantaneous velocity?
when the velocity is constant
Which of the five graphs in (Figure 1) shows velocity versus time for ball A? Assume downward direction is positive.Which of the five graphs in the figure shows velocity versus time for ball B? Assume downward direction is positive
3/none of these
Brick A is dropped from the top of a building. Brick B is thrown straight down from the same building, and neither one experiences appreciable air resistance. Which statement about their accelerations is correct?
The two bricks have exactly the same acceleration.
The slope of a velocity versus time graph gives
acceleration
Once you have selected a coordinate system, you can express a two-dimensional vector using a pair of quantities known collectively as __________.
components
The position-time graph for an object moving with constant acceleration starts off with zero slope. At later times the slope is positive. initial velocity is...
zero
A child standing on a bridge throws a rock straight down. The rock leaves the child's hand at time t = 0 s. If we take upward as the positive direction, which of the graphs shown below best represents the velocity of the stone as a function of time?
(c)Line starts below x axis and is slanted down
A child throws a baseball directly upward. What are the signs of the velocity and acceleration of the ball immediately after the ball leaves the child's hand?
+,-
An elevator is moving downward when someone presses the emergency stop button. The elevator comes to rest a short time later. Give the signs for the velocity and the acceleration of the elevator after the button has been pressed but before the elevator has stopped.
-,+
A child throws a baseball directly upward. What are the signs of the velocity and acceleration of the ball at the very top of the ball's motion (i.e., the point of maximum height)?
0,-
