In figure 5.11 , if Carol pushed with a force of 30 N instead of 25 N, the box w
ID: 1883980 • Letter: I
Question
In figure 5.11 , if Carol pushed with a force of 30 N instead of 25 N,
the box would move with a faster constant velocity.
the box would move with constant acceleration.
the box would move with the same constant velocity.
the box would move with increasing acceleration.
Figure 5.11 is this :
Which of the following statements are correct, regarding a falling soccer ball? (Circle all that are correct, there may be more than one.)
A) As it speeds up the drag force gets bigger.
B) As it speeds up the net force on the soccer ball gets smaller.
C) As it speeds up the magnitude of the acceleration gets less.
D) As it speeds up the acceleration will eventually reach zero - assuming it falls from a great enough height.
A)the box would move with a faster constant velocity.
B)the box would move with constant acceleration.
C)the box would move with the same constant velocity.
D)the box would move with increasing acceleration.
Explanation / Answer
From Newton's Second Law of motion , the net force on a body equals the product of it's mass and the acceleration in the direction of force.In the first case when the sofa is moving with constant velocity, the acceleration is zero. So the applied force and the kinetic frictional force must be equal and opposite. Implies that the kinetic frictional force is Fk = 25 N.
Now in the second case, applied force is F = 30 N, so the net force is Fnet = F - Fk = 5 N, so there is some constant net force and so there will be a constant acceleration.
Option - b) the box would move with constant acceleration.
the drag force is proportional to the square of the velocity. so more velocity means more drag.
As the ball falls through a great height, net force on the ball is zero. Thus aacceleration=0
so options (a) and (d) are correct.