Module 4 - quarterly test 1 Flashcards
Explain how you should look at two-dimensional situations so as to make them as easy as possible to analyze.
You should always try to see the one-dimensional problems that make up the two-dimensional situation
What do we know about the x- and y-components of a projectile’s velocity when the projectile is at its maximum height?
the y-component of its velocity is zero. The x-component is the same as when the projectile was launched.
A projectile lands at a height equal to the height at which it was launched after a total flight time of 4.0 seconds. How many seconds after launch does it reach its maximum height?
2.0 seconds
A projectile is fired upwards with a speed of 150 m/sec. When it once again reaches the height from which it was launched, what is its speed?
150 m/sec
What happens to the y-component of a projectile’s velocity as the projectile travels through the air?
When the projectile is first launched, the y-component of its velocity continually decreases until it reaches zero. After that, the y-component becomes more and more negative until the projectile hits the ground.
If a projectile is fired in empty space, will it still follow a parabolic path? Why or why not?
No. Since there is no gravity, there will be no acceleration in the y-dimension.
A sharpshooter tells a nervous man to hold out a can at arm’s length. The sharpshooter says that he will shoot the can out of the man’s hand. The sharpshooter realizes, however, that the nervous man will be scared at the sound of the gun and will drop the can as soon as the gun fires. In order to still hit the can, should the sharpshooter aim above, below, or straight at the can?
Directly at the can.
In the question above, suppose the man holding the can is not nervous, and the sharpshooter know that he will hold onto the can even after the gun is fired. Should the sharpshooter aim above, below, or at the can in order to hit it?
the sharpshooter must aim above the can
What have we ignored when solving all of the projectile motion problems that we have done?
air resistance
What is parabolic motion?
Motion that occurs when an object moves in two dimensions but has zero acceleration in one of those dimensions and a constant, non-zero acceleration in the other
When is an object’s path parabolic?
When a projectile is fired or thrown near the surface of the earth
What is range?
the distance that a projectile travels in the x-dimension
What requirement must be met to use the range equation (4.9)?
the projectile must land at the same height from which it is launched.
Is gravitational acceleration positive or negative when you put it into the range equation?
Positive
