Unit 3 Concepts

A plane flying horizontally at a speed of 50.0 m/s and at an elevation of 160 m drops a package. Two seconds later it drops a second package. How far apart will the two packages land on the ground?

100 m

At what point of the ball's path shown in the figure above is the vertical component of the ball's velocity zero?

B

When a football in a field goal attempt reaches its maximum height, how does its speed compare to its initial speed?

It is less than its initial speed

Without air resistance, a projectile fired horizontally at 8 km/s from atop a mountain would

all of these

A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air drag, its vertical component of velocity

decreases

In the figure above, the horizontal component of the ball's velocity at A is

equal to the horizontal component of its initial velocity

At what angle should a water-gun be aimed in order for the water to land with the greatest horizontal range?

45°

A stone is thrown horizontally from the top of a cliff. One second after it has left your hand, its vertical distance below the top of the cliff is

5 m

A projectile is launched vertically upward at 50 m/s. If air resistance is negligible, its speed upon returning to its starting point is

50 m/s

For the winter, a duck flies 10.0 m/s due south against a gust of wind with a speed of 2.5 m/s. What is the resultant velocity of the duck?

7.5 m/s south

A projectile is launched at ground level an angle of 15 degrees above the horizontal and lands down range. What other projection angle for the same speed would produce the same down-range distance?

75 degrees

A bullet is fired horizontally, and at the same instant a second bullet is dropped from the same height. Ignore air resistance. Compare the times of fall of the two bullets.

They hit at the same time

A bullet fired horizontally from a rifle begins to fall

as soon as it leaves the barrel

Two balls are thrown horizontally. Ball C is thrown with a force of 20 N, and ball D is thrown with a force of 40 N. Assuming all other factors are equal, ball D will fall toward the ground

at the same rate as ball C

A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air drag, its horizontal component of velocity

remains unchanged

The path of a projectile through space is called its:

trajectory

An Olympic athlete throws a javelin at four different angles above the horizontal, each with the same speed: 30°, 40°, 60°, and 80°. Which two throws cause the javelin to land the same distance away?

30° and 60°

A projectile is fired into the air at an angle of 50 degrees with the ground and lands on a target that is at the same level at which the projectile started. It will also land on the target if it is fired at an angle of

40 degrees

A ball is thrown at an original speed of 8.0 m/s at an angle of 35° above the horizontal. What is the speed of the ball when it returns to the same horizontal level?

8.0 m/s

In the figure above, at which point is the ball's speed about equal to the speed at which it was tossed?

C

In the figure above, the magnitude of the ball's velocity is greatest at location

D

A projectile is fired horizontally in a region of no air resistance. The projectile maintains its horizontal component of velocity because

it is not acted on by any horizontal forces

A soldier throws a grenade horizontally from the top of a cliff. Which of the following curves best describes the path taken by the grenade?

parabola

Which of the following is the motion of objects moving in two dimensions under the influence of gravity?

projectile motion

Roll a bowling ball off the edge of a table. As it falls, its horizontal component of velocity

remains constant

A bullet fired horizontally over level ground hits the ground in 0.5 second. If it had been fired with twice the speed in the same direction, it would have hit the ground in

0.5 s

An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward at an angle instead, its acceleration will be

1 g downward

The figure above shows the path of a ball tossed from a building. Air resistance is ignored. In the figure above, the magnitude of the ball's velocity is least at location

B

Which of the following does not exhibit parabolic motion?

a flat piece of paper released from a window

Which of the following is not an example of projectile motion?

a hot-air balloon drifting toward Earth

What is the path of a projectile (in the absence of friction)?

a parabola

Which of the following is an example of projectile motion?

a thrown baseball

A pilot drops a bomb from a plane flying horizontally at a constant speed. Neglecting air resistance, when the bomb hits the ground the horizontal location of the plane will

be over the bomb

You are throwing a ball for the second time. If the ball leaves your hand with twice the velocity it had on your first throw, its horizontal range R (compared to your first serve) would be

four times as much

The diagram below shows the trajectories of two balls. The magnitude of the initial velocity is vi, the launch angle is q, and the horizontal and vertical components of the initial velocity are vxi and vyi. Compare the values of qi. The value for ball A

is equal to the value for ball B

The diagram below shows the trajectories of two balls. The magnitude of the initial velocity is vi, the launch angle is q, and the horizontal and vertical components of the initial velocity are vxi and vyi. Compare the values of vi. The value for ball A

is greater than the value for ball B

The diagram below shows the trajectories of two balls. The magnitude of the initial velocity is vi, the launch angle is q, and the horizontal and vertical components of the initial velocity are vxi and vyi. Compare the values of vxi. The value for ball A

is greater than the value for ball B

The diagram below shows the trajectories of two balls. The magnitude of the initial velocity is vi, the launch angle is q, and the horizontal and vertical components of the initial velocity are vxi and vyi. Compare the values of vyi. The value for ball A

is greater than the value for ball B

A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?

the dropped one

A hunter on level ground fires a bullet at an angle of 2 degrees below the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?

the fired one

A stone is thrown horizontally from the top of a tower at the same instant a ball is dropped vertically. Which object is traveling faster when it hits the level ground below?

the stone