Module 2 - quarterly test 1 Flashcards
What 2 conditions must be met before you can use the three equations we derived in this module?
Motion must always occur in a straight line, and the acceleration of the object must be constant
What is air resistance? How does air resistance affect the acceleration of a falling object?
Air resistance reduces the acceleration of objects that are falling. It arises because an object that falls must shove the molecules and atoms which make up the air out of the way in order to fall. Those molecules and atoms resist the showing, which reduces the object’s acceleration
What is the definition of free fall?
the motion of an object when it is falling solely under the influence of gravity
A very picky physicist says that no object can really experience free fall when falling near the surface of the earth. Explain why the physicist is technically correct.
Since all objects falling near the surface of the earth are in air, they all experience air resistance, which means they are not falling solely under the influence of gravity.
Even though the physicist in question 4 is technically correct, explain why we can still assume that most objects falling near the surface of the earth are, indeed, in free fall.
many objects are not strongly affected by air resistance
If an object is thrown up in the air, where is its velocity zero? When its velocity is zero, what is its acceleration?
the object’s velocity is zero at the maximum height that it attains. Its acceleration is always 9.8 m/sec2 downwards, even when its velocity is zero.
On the moon, gravity is significantly weaker than on earth. Would you expect the acceleration due to gravity on the moon to be larger, smaller, or the same as compared to the acceleration due to gravity on earth?
Since gravity is weaker on the moon, it cannot accelerate things as strongly. Thus, the acceleration due to gravity on the moon is smaller than that of earth.
A feather and a penny are put in a long glass tube and all of the air is sucked out of the tube. While inside the tube, will the feather fall faster than, slower than, or the same as the penny?
there is not air resistance, and they are both affected only by gravity, which is the same for all objects, therefore they both fall at the same rate.
A ball is thrown up in the air with an initial velocity of 1.2 m/sec. If the ball is caught at exactly the same height from which it was thrown, what will its velocity be?
When the ball returns to the place it was thrown, it has equal and opposite velocity, so it will be -1.2 m/sec.
Suppose you have two balls of equal mass. Although their masses are equal, they are mad of different substances. As a result, the first ball is significantly smaller than the second ball. Which ball has the highest terminal velocity?
the first ball will have the higher terminal velocity
What is free fall?
The motion of an object when it is falling solely under the influence of gravity
What acceleration do objects falling near the surface of the earth experience?
constant acceleration of 9.8 m/sec2 or 23 feet/sec2 straight down
Does acceleration due to gravity depend on the nature of the object experiencing free fall?
no, it is independent of the nature of the object, as long as it has mass
What is air resistance?
The drag that air produces on objects traveling through it
What will the velocity of an object be when it reaches maximum height?
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