Vertical Projectiles
An object falls freely from rest for three seconds. The acceleration of the object is
What equation is used only in the x-dimension?
v = d / t
What shape is the trajectory of a projectile?
A parabola
How far a projectile travels horizontally; how far a projectile travels vertically.
Velocity, displacement, force, acceleration
A seagull drops a clam from the air. It takes 3.0 seconds to hit the ground. What was the approximate height from which the clam was dropped?
45 meters
Describe how the horizontal velocity of a projectile changes as it travels through its parabola.
It doesn't; the velocity is constant in the x direction.
A ball is kicked with an initial velocity of 5.0 meters per second at a 30-degree angle from the horizontal. As the ball rises, what happens to the vertical component of its velocity?
It decreases
Name one variable you ALWAYS have in the Y-direction.
What is the displacement traveled if a delivery driver drives 3 kilometers north, then 4 kilometers east?
5,000 meters NE
A stone is dropped from a bridge 45 meters above the surface of a river. Approximately how many seconds does the stone take to reach the water's surface?
3.0 seconds
A ball is projected horizontally with an initial velocity of 20 m/s off a 100-meter-high cliff. If the ball hits the ground 90 meters away, how long was it in the air?
4.5 seconds
A batted softball leaves the bat with an initial velocity of 44 meters per second at an angle of 37 degrees above the horizontal. What is the magnitude of the initial vertical component of the softball's velocity?
26.5 m/s
What is the only variable that you can use in both dimensions?
Time
A car, starting from rest, accelerates at 4 m/s/s. What is its velocity at the end of 8 seconds?
32 m/s
A ball is thrown straight up with a speed of 12 m/s near the surface of Earth. What is the maximum height reached by the ball?
7.3 meters
An object is thrown horizontally off a cliff with an initial velocity of 5 m/s. The object strikes the ground 3 seconds later. What is the horizontal speed of the object 1 second after it is released?
5 m/s
A kicked soccer ball has an initial velocity of 25 meters per second at an angle of 40 degrees above the horizontal. Calculate the maximum height the ball reaches above its initial position.
13.2 meters
How can you find the different components of velocity when an initial velocity is applied to an object at an angle?
When solving for x, plug in the velocity cosine theta. When solving for y, plug in the velocity sine theta.
An unbalanced force of 20 Newtons is applied to a 4 kilogram object at rest. The acceleration of the object is closest to
5 m/s/s
A student wishes to record a 7.5-kilogram watermelon colliding with the ground. Calculate how far the watermelon must fall freely from rest so it would be traveling at 29 meters per second the instant it hits the ground.
42.9 meters
A pool ball leaves a 0.60-meter high table with an initial horizontal velocity of 2.4 m/s.
a. Predict the time required for the pool ball to fall to the ground and
b. The horizontal distance between the table's edge and the ball's landing location.
a. 0.35 seconds
b. 0.84 meters
An outfielder throws a baseball to the first baseman at a speed of 19.6 m/s at an angle of 30 degrees above the horizontal. If the ball is caught at the same height from which it was thrown, calculate how long the ball was in the air AND how far the throw was.
1.998 seconds; 33.91 meters
Explain how you can tell which velocity (final or initial) you have when solving in the Y-direction.
If thrown straight out horizontally or dropped from rest, you have the initial velocity. If you're solving for the maximum height, you have the final velocity. It is 0 in both cases.
A 10 Newton block is sliding down a 30-degree incline at a constant speed. What is the normal force of the block?
8.6 Newtons