a car traveling at 24 m/s starts to decelerate steadily. It comes to a complete stop in 6 seconds what is its acceleration?
1 answer:
We can solve for the acceleration by using a kinematic equation. First we should identify what we know so we can choose the correct equation.
We are given an original velocity of 24 m/s, a final velocity of 0 m/s, and a time of 6 s. We and looking for acceleration (a) in m/s^2.
The following equation has everything we need:
So plug in the known values and solve for a:
0 = 24 + 6a
-24 = 6a
a = -4 m/s^2
We are given an original velocity of 24 m/s, a final velocity of 0 m/s, and a time of 6 s. We and looking for acceleration (a) in m/s^2.
The following equation has everything we need:
So plug in the known values and solve for a:
0 = 24 + 6a
-24 = 6a
a = -4 m/s^2
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Answer:
Under the reasonable assumption that the brick has more mass than the feather, the brick experiences a greater force of air friction.
Explanation:
<u>Objects at terminal velocity</u>, only under the influence of gravity, have maximized their speed and <u>have an acceleration of zero</u>. Thus, neither object is accelerating.
Recall Newton's second law:
Since acceleration for each object is zero, the sum of the force acting on each of those objects must also be zero.
Since the only forces acting on the objects are gravity and the force of air friction, in order to zero out, <u>the force of air friction must be equal in magnitude and opposite in direction to the force of gravity</u>.
Recall that near the surface of the earth, , so <u>the Force of Gravity acting on an object is directly proportional to the object's mass</u>. <em>(A similar argument could be made even if this were not taking place on the surface of the earth, so long as the objects were the same distance from the object providing gravitational influence).</em>
If the masses of the objects are different, <u>the object with the greater mass will experience</u> a larger force of gravity, and hence <u>a larger force of air friction</u> at terminal velocity.
Under the reasonable assumption that the brick has more mass than the feather, the brick experiences a greater force of air friction.