Physics: edX Projectile Motion

A dart gun can shoot darts with a velocity of 36m/s . A curious physics student aims the dart gun at a 60∘ angle above the horizontal and fires a dart. The dart reaches its maximum height and falls about halfway down when it lands in an open window 23m above the ground. What is the magnitude of the dart's velocity, in m/s, at the moment it enters the window?

29

A baseball is thrown down a hill. This baseball has on-board sensors that can measure its velocities in both the x- and y- directions. The data show that the ball took off with an initial velocity in the y-direction of +4.0m/s and had a final velocity in the y-direction of −5.8m/s. How much lower was the ball when it landed compared to where it started? To paraphrase: What was the magnitude of the vertical displacement of the ball?

0.90 m

A baseball is thrown down a hill. This baseball has on-board sensors that can measure its velocities in both the x- and y- directions. The data show that the ball took off with an initial velocity in the y-direction of +4.0m/s and had a final velocity of −5.8m/s. Calculate the hang time of the ball.

1.0 s

A projectile is launched with an initial velocity of 100.0m/s at a 30∘ angle off of the horizontal. Calculate the maximum height achieved by the projectile.

127 m

A 0.500kg hammer, a 6.4kg bowling ball, a baseball and a tennis ball are all released from rest at the same time from the top of a 50m cliff. How much time does it take for them to reach the ground? Use 9.8m/s2 for g.

3.2 sec

A projectile is launched with an initial velocity of 100.0m/s at a 30∘ angle off of the horizontal. What is the velocity of the projectile at the highest point in its path?

86.6 m/s

In an experiment, a student launches a ball with an initial horizontal velocity at an elevation 2m above ground. The ball follows a parabolic trajectory until it hits the ground. Which of the following accurately describes the graph of the ball's vertical velocity vs. time (taking the downward direction to be negative)

A gradually increasing negative value (straight line) correct

A ball is thrown at an angle of 45° above the horizontal. Which of the following best describes the acceleration of the ball from the instant after it leaves the thrower's hand until the time it hits the ground? Ignore air resistance.

Always in the downward direction with the same constant value

Two golfers at a driving range hit golf balls at the same moment. In both shots, the initial upwards velocity of the two balls is the same. The first golfer's shot had a larger initial horizontal velocity than the second golfer's shot. Which ball hits the ground first?

Both at the same time

A soccer ball is kicked with an initial speed and at an angle θ. Which of the following statements is true?

The initial horizontal component of the velocity is equal to the final horizontal component of the velocity.

Celia and Jane are on the roof of their school. Each woman has an identical ball that they release from the roof at the same time. However, while Celia drops her ball from rest, Jane releases her ball with a small horizontal velocity. Assuming that air resistance is negligible, which ball will hit the ground first?

The two balls hit the ground at the same time

A 0.500kg hammer, a 6.4kg bowling ball, a baseball and a tennis ball are all released from rest at the same time from the top of a 50m cliff. Assuming there a negligible amount of drag force, which arrives at the ground first?

They all hit the ground at the same time

Which of the following factors might affect the height above the target that the professor must aim, if you consider a real-life situation?

Wind blowing toward the professor, Wind blowing from behind the professor, A greater initial velocity of the arrow

If you took a cannon to a very tall mountain and shot a cannonball horizontally, which of the following scenarios are possible?

all of the above are possible

A girl throws a ball horizontally from a roof 10 meters high. If air resistance is negligible, the vertical velocity of the ball ______________ its horizontal velocity.

does not depend on

A dart gun can shoot darts with a velocity of 36m/s . A curious physics student aims the dart gun at a 60∘ angle above the horizontal and fires a dart. The dart reaches its maximum height and falls about halfway down when it lands in an open window 23m above the ground. How much time did the dart rise and how much time did it spend falling?

time to rise 3.18s time to fall 2.33s