Physics Chapter 3 reading assignment & HW

Select all motions that involve acceleration

-A car negotiating a curved road, moving with a constant speed. -A car speeding up in the positive direction. -A car slowing down in the negative direction.

An object thrown down with initial velocity v0 hits the ground after 4 seconds. Select all the options that are correct.

-A graph showing how far the object travels with time will be a parabola. -The object will hit the ground earlier than another object dropped from the same height. -If v0 is increased, the time it takes to hit the ground would decrease.

Three balls are projected horizontally from a table that is 1.0 m high with initial horizontal velocities v1 = 10 m/s, v2 = 20 m/s, and v3 = 30 m/s. Select all the correct statements about the motion of the balls.

-All the balls will have the same vertical velocity right before they hit the ground. -After falling 1 m, the ball with velocity v3 will have traveled horizontally three times as far as the ball with velocity v1. -All the balls will hit the ground at the same time.

When you throw a ball straight upward, the ball stops momentarily before it reverses direction and falls down. Which of the following is correct?

-At the maximum height, the velocity is zero. -As the ball goes up and down, the acceleration is constant and is always pointing down. -The velocity of the ball decreases then increases.

Object A is thrown straight up with an initial velocity of 10 m/s and object B is thrown straight down with an initial velocity of 5 m/s. Select all the options which accurately describe the situation after 2 seconds.

-Both objects will have changed their velocities by the same amount. -Object A will have a lower velocity than object B.

Select the option that explains why Galileo rejected Aristotle's theory describing the motion of falling objects.

-Galileo relied on experiments that proved Aristotle wrong. -Aristotle's observations did not take all relevant factors (e.g., air resistance) into account.

One ball is thrown straight upward with an initial velocity v0. At the same time, a second ball is launched from the same place with an initial angle θ = 30° and the initial velocity v1. Which of the following is correct?

-If the initial angle θ is increased, you will have to decrease the initial velocity to reach the same height. -Both balls will reach the same height if the vertical component of v1 is equal to v0.

For a projectile thrown at some angle greater than zero but less than ninety degrees, at a given moment, which of the following could be true about its velocity? You may choose more than one.

-Its velocity could have both vertical and horizontal components. -Its velocity could be exclusively horizontal.

A dropped ball, starting from rest, accelerates downward. Select all the answers that describe its motion.

-The ball falls faster during the fourth second than it did during the first second. -The equation d = 1/2 at^2 can be used to calculate the distance traveled by the ball.

You throw a ball straight upward with an initial velocity v0 = 30 m/s. Select all the options that correctly describes the motion of the ball. Use g ≈ 10 m/s2 pointing down.

-The ball travels the same distance during the first 3 seconds as it does during the next 3 seconds. -The ball will travel farther during the 0 to 1 second interval than during the period from 2 to 3 seconds.

Two cars are moving in the same direction. They have accelerations a1 = 4.0 m/s^2 and a2 = 6.0 m/s^2. Based on this information, select the correct answers.

-The car with a larger acceleration has a larger increase in velocity in the same period of time. -If both cars started from rest, one car always moves 1.5 times faster than the other.

An object is projected with an initial angle θ0 = 30° and an initial velocity v0. Select all the options that describe the motion of the object.

-The horizontal velocity of the object is constant. -The object will travel horizontally equal distances in equal times.

Objects A and B have masses mA and mB, respectively. They are thrown down at the same time from the same height with initial speeds vA = 10 m/s and vB = 30 m/s. Select all the statements that correctly describes the motion of both objects. Ignore air resistance.

-The velocity of both masses will increase equal amounts in equal times. -A plot of velocity changes with time for both masses will show parallel straight lines.

In a projectile motion, how many launch angles would give the same range.

-Two angles for any range other than the maximum range -Only one angle if the range is the maximum range

Object B is thrown straight up with an initial velocity v0. Taking the upward direction as positive, select all the statements that describe the motion. (Ignore air resistance.)

-When the object returns to its initial position, its velocity is --v0. -It takes the same time to go up to its maximum height as it takes to come down to the original position.

An object is definitely accelerating if it is

-changing velocity. -slowing down. -speeding up.

Galileo wanted to measure the acceleration due to gravity experimentally. For that he

-used his own pulse to measure the time. -used an inclined plane to slow down the falling motion.

An object is projected with an initial angle θ0 = 30°, an initial horizontal velocity v0x = 26m/s, and an initial vertical velocity v0y = 15 m/s. After 1 second, the object has moved horizontally a distance of _______ and vertically a distance of _________. (Use the simplification that g = 10 m/s^2.)

26 10

If the launch velocity is the same, which launch angle gives the maximum range?

45 degrees

A projectile is launched with initial velocity v0 such that the vertical component is v0y = 3 m/s and the horizontal component is v0x = 4 m/s. The magnitude of the initial velocity is equal to

5 m/s

A ball is projected horizontally from a table 1.0 m high and hits the ground after falling for a time t = 0.45 s. If the ball travels horizontally a distance x = 3.0 m in that time, its initial velocity was equal to m/s.

6.67m/s

If the launch velocity is the same, which launch angle gives the highest peak?

85 degrees

Object A is dropped and allowed to fall for 1 second. Object B is dropped and allowed to fall for 3 seconds. Object B will fall ________ times farther than object A.

9

Three balls are projected horizontally from a table that is 1.0 m high with initial horizontal velocities v1 = 10 m/s, v2 = 20 m/s, and v3 = 30 m/s. Select all the correct statements about the motion of the balls.

All the balls will hit the ground at the same time. All the balls will have the same vertical velocity right before they hit the ground. After falling 1 m, the ball with velocity v3 will have traveled horizontally three times as far as the ball with velocity v1.

Galileo used an inclined plane to slow down the falling motion so that he could measure the acceleration due to gravity. What was his rationale for using the inclined plane?

Along an inclined plane, only part of gravity acts on the object in its direction of motion.

If an object is dropped from a height of 10 m, which of the following statements are true?

At any point during the fall, neither the velocity nor acceleration depends on the mass of the object.

Object A is thrown straight up with an initial velocity of 10 m/s and object B is thrown straight down with an initial velocity of 5 m/s. Select all the options which accurately describe the situation after 2 seconds.

Both objects will be traveling downward.

The baseball slows down as it goes up.

Both velocity and acceleration point downward.

While an object is falling, its acceleration will remain _________ but its velocity will ______

Constant, Increase

A careless child drops his toy out the window of a moving car. Where will the toy hit the ground? Ignore air resistance.

Directly below the child's window.

True or false: When a brick and a feather are dropped at the same time from the same height, the brick reaches the floor first because it is heavier; therefore, it has a larger gravitational acceleration.

False

If an object is in free fall, what forces are acting on it?

Gravity

A car is moving east, with a velocity v = 20 m/s. Based on this information, what can you say about the motion?

If the car is speeding up, the acceleration must point east.

An object is thrown straight up into the air. While it is in the air, choose where it has the greatest acceleration.

It is the same everywhere.

Whether you throw a ball upward or downward,

Its acceleration is always pointing downward.

An eraser is dropped (straight down) from a table at the same time that a sharpener (on the same table) is thrown horizontally. Which of the following statements is correct (ignore air resistance)?

The eraser will hit the ground closer to the table. Both the eraser and the sharpener will hit the ground the same time.

A ball is launched with an initial velocity v0 and an angle θ from the ground. Assuming a horizontal flat area and ignoring air resistance, select the statement that correctly describes the motion

The final speed, when the ball hits the ground, is equal to the initial speed.

A ball is launched with an initial velocity v0 and an angle θ from the ground. Assuming a horizontal flat area and ignoring air resistance, select the statement that correctly describes the motion.

The final speed, when the ball hits the ground, is equal to the initial speed.

The object is moving with constant speed.

The graph is a horizontal line

The object is speeding up.

The graph is a straight line with a negative slope.

The object is slowing down

The graph is a straight line with a positive slope.

A hunter with a blowgun saw a monkey hanging in a tree. The hunter aimed at the monkey and fired his blowgun at the same instant the monkey released its grip on the branch. Which of the following is correct?

The hunter will hit the monkey provided the distance to the branch is not too great.

An object is projected with an initial angle θ0 = 30° and an initial velocity v0. Select the option that describes the motion of the object.

The object travels horizontally equal distances in equal times.

An object is thrown straight upward. Select the option that best describes the situation at its maximum height.

The velocity and speed are equal to zero while the gravitational acceleration points down.

A teenager riding a bicycle in a straight line at constant speed wants to toss an apple up in the air and catch it. What must she do?

Throw the apple straight up.

The book speeds up as it falls.

Velocity points up and acceleration points downward.

A ball rolling rapidly along a tabletop rolls off the edge and falls to the floor. At the exact instant that the first ball rolls off the edge, a second ball is dropped from the same height. Which ball, if either, reaches the floor first?

both balls reach the floor at the same time

A hunter with a blowgun saw a monkey hanging in a tree. The hunter aimed at the monkey and fired his blowgun at the same instant the monkey released its grip on the branch. The hunter will hit the monkey because

both the projectile and the monkey fall down at the same rate.

A freely falling object (neglecting air resistance) has its velocity

increase linearly with time.

During every second after an object is dropped from rest and experiences free fall, its speed

increases by approximately 10 m/s.

A ball is thrown straight upwards and then returns to the Earth. How does the acceleration vector change during this motion?

it remains downwards the entire time

After it passes the peak of the path of its motion, an object thrown upward has

its velocity directed downward and its acceleration directed downward.

Just before it reaches the peak of the path of its motion, an object thrown upward has

its velocity directed upward and its acceleration directed downward.

two different trajectories are shown for a ball thrown by a center fielder to home plate in a baseball game. Is the ball's velocity zero at the highest point of the trajectory?

no, for both trajectories

A hunter with a blowgun saw a monkey hanging in a tree. The hunter aimed at the monkey and fired his blowgun at the same instant the monkey released its grip on the branch. the hunter will hit the monkey

regardless of whether the monkey was light or heavy.

A ball is thrown with an initial angle θ = 30° and an initial speed v1. A second ball is thrown from the same height with an initial angle θ = 45°. If both balls reach the same maximum height, the initial speed of the second ball is

smaller than v1.

Two identical pieces of paper, one crumpled into a ball and the other left uncrumpled, are released simultaneously from the same height above the floor. Which one, if either, do you expect to reach the floor first?

the crumpled paper

In shooting a free throw in basketball, what is the primary advantage that a high, arching shot has over one with a flatter trajectory?

the higher arched shot has a larger range of successful trajectories

An expert marksman aims a high-speed rifle directly at the center of a nearby target. Assuming the rifle sight has been accurately adjusted for more distant targets, how will the bullet strike the target

too high

A small piece of paper is dropped and flutters to the floor. At what point, if any, during the paper's motion is it accelerating?

upon being dropped

Along the trajectory of a projectile, the____________ component of the acceleration remains constant and pointing down while the ____________ component is equal to zero.

vertical or y horizontal or x