physics projectiles

A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 100m/s, where will the cannonball be 1 second later (neglect air resistance)?

100 m downrange

A bullet shot at 600m/s horizontally hits a target 175m away. How far does the bullet fall before it hits the target?

175/600=t=0.29s dy=4.9(0.29) squared= 0.41m

When the ball above reaches its highest point, the instantaneous speed is. . .

0 m/s

A projectile shot with an initial velocity of 100m/s at an angle of 60 degrees follows a parabolic path and hits a stationary ballon a the top of its trajectory. With what horizontal speed does the projectile hit the ballon?

Vx= 100m/s times cos60= 50m/s

If you drop a feather and a coin at the same time in tube filled with air, which will reach the bottom if the tube first?

the coin

A ball thrown upward is caught when it comes back down. In the absence of air resistance, the acceleration of the ball when caught is. . .

the same acceleration it had when thrown upward

A ball thrown upward is caught when it comes back down. In the absence of air resistance, the speed of the ball when caught is. . .

the same as the speed it had when thrown upward

After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)?

the same as when it was at the top of its path

A ball thrown upward is caught when it comes backdown. In the absence of air resistance, the velocity of the ball when caught is. . .

the same magnitude as, and opposite in sign to, the velocity it had when thrown upwards

At what angle is a maximum range reached by a projectile?

45 degrees

What is the resultant of a 4 unit vector and a 3 unit vector at right angles to each other?

5 units

Which of the following statements are true of projectiles? list all that apply.

a projectile is a free-falling object, a projectile experiences negligible or no air resistance, a projectile must be accelerating in the downward direction, a projectile does not have to have horizontal motion, a projectile could begin its projectile motion with a downward velocity, and a projectile does not need to be "falling."

Which of the following statements are true of the horizontal motion of projectiles? list all that apply.

a projectile with a horizontal component of motion will have a constant horizontal velocity and the horizontal velocity of a projectile is unaffected by the vertical velocity; these two components of motion are independent of each other.

Which of the following is an example of projectile motion?

a softball being thrown

A golf ball hit at 30m/s at an angle of 40 degrees above the horizontal? a. What was the initial horizontal velocity? b. What was the initial vertical velocity? c. How long did it remain in the air? d. How far didi it go?

a. 30m/s times cos40= 23m/s b. 30m/s times sin40= 19.28m/s c. V2= 19.28m/s 1.965= t d. 23m/s times 3.93= 90.3m

Harry Potter accidentally fell off of is broom which was traveling horizontally at 15m/s. He plunged into the water below him 1.7 seconds later. Assuming no air resistance and no "levilosum" charm. . .

a. what is the horizontal distance he travels while falling? 15m/s times 1.7s= 25.5m b. what is his horizontal velocity at the moment of impact? 15m/s c. what is his vertical velocity at the moment of impact? V2= -9.8m/s times 1.7s= -16.6m/s

When the ball above reaches its highest point, the magnitude of its acceleration is. . .

about 10 m/s2

In the absence of air resistance, objects fall at constant. . .

acceleration

In the absence of air resistance, the vertical component of a projectile's velocity does not change as the projectile moves?

always false

In the absence of air resistance, the horizontal component of the projectile's velocity does not change as the projectile moves?

always true

At what part of a path does a projectile have minimum speed?

at the top of its path

A ball tossed vertically upward rises, reaches it highest point, and then falls back to its starting point. During this time, the acceleration of the ball is always. . ?

directed downward

An object is projected horizontally at 7.0m/s from the top of a 135m cliff. How far from the base of the cliff will the object strike the ground?

dx=36.4m and t=5.2s

A ball is thrown into the air at some angle. At the very top of the ball's path, its velocity is. . .

entirely horizontal

If a rock is thrown horizontally from the same height and at the same time another rock is dropped, which will hit the ground first?

neither

At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?

neither, they hit the ground at the same time

If you drop a feather and a coign at the same time in a vacuum tube (the absence of atmosphere) which will reach the bottom of the tube first?

neither, they will reach the bottom at the same time

Which of following statements are true of the time of flight for a projectile? list all that apply.

the time that a projectile is in the air dependent upon the vertical component of the initial velocity, for a projectile which lands at the same height that it is projected from, the time to rise to the peak is equal to the time to fall from its peak to the original height, and for the same upward launch angles, projectiles will stay in the air longer if the initial velocity is increased.

Which of the following statements are true of the vertical motion of projectiles? list all that apply

the vertical component of a projectile's velocity is changing, the vertical component of a projectile's velocity is changing at a constant rate, and a projectile with a downward component of motion will have a downward component of acceleration.

The horizontal comment of a projectiles velocity is independent of. . .

the vertical component of tis velocity

As an object falls freely in the absence of air, its. . .

velocity increases in magnitude

Suppose an object is in free fall. Each second the object falls. . .

with the same average speed

A ball thrown upward is caught when it comes back down. In the absence of air resistance, the displacement of the ball when caught is. . .

zero, and the air resistance has nothing to do with it