Force and Motion Dynamics
A ball of mass is dropped from rest and experiences air resistance given by , where is a positive constant. Given that the initial velocity is zero, what is the velocity of the ball as a function of time?
v(t) = rac{mg}{k}(1 - e^{-rac{k}{m}t})
v(t) = rac{mg}{k}e^{-rac{k}{m}t}
v(t) = rac{mg}{k}(1 + e^{-rac{k}{m}t})
v(t) = rac{mg}{k}(e^{rac{k}{m}t} - 1)
An object falls through the air, experiencing a resistive force. Which of the following changes would result in a smaller time constant ()?
Increasing the mass of the object.
Decreasing the mass of the object.
Decreasing the constant (the resistive force coefficient).
Increasing the air density.
Under what condition does an object reach terminal velocity when falling through a fluid?
When the object's acceleration is at its maximum.
When the object's velocity is zero.
When the net force on the object is zero.
When the object's mass is zero.
A skydiver is falling towards the Earth. Which of the following statements accurately describes the direction of the resistive force acting on the skydiver?
The resistive force acts in the same direction as gravity.
The resistive force acts perpendicular to the direction of motion.
The resistive force acts in the opposite direction to the skydiver's motion.
The resistive force acts in a random direction.
A sphere of mass 2 kg falls through a fluid with a resistive force , where is the velocity in m/s. What is the time constant for this system?
0.5 s
2 s
8 s
16 s
An object of mass is falling under the influence of gravity and a resistive force proportional to its velocity, given by , where is a constant. Which of the following differential equations correctly describes the motion ...
mrac{dv}{dt} = mg + kv
mrac{dv}{dt} = -mg - kv
mrac{dv}{dt} = mg - kv
mrac{dv}{dt} = -mg + kv
Which of the following acceleration-time graphs best describes the motion of an object that is dropped from rest and experiences air resistance?
A horizontal line at .
A horizontal line at 0.
A curve starting at and asymptotically approaching 0.
A curve starting at 0 and asymptotically approaching .

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A 5 kg object falls through the air and experiences a resistive force given by , where is in m/s. What is the terminal velocity of the object?
2.5 m/s
5 m/s
24.5 m/s
49 m/s
An object reaches a terminal velocity when falling through air. If the mass of the object is doubled, what happens to the new terminal velocity, assuming the resistive force is still proportional to velocity?
The terminal velocity remains the same.
The terminal velocity is halved.
The terminal velocity is doubled.
The terminal velocity increases by a factor of .
A ball is dropped from a height and reaches terminal velocity. Which of the following statements about the velocity-time graph of the ball is correct?
The graph is a straight line with a positive slope.
The graph is a straight line with a negative slope.
The graph is a curve that approaches a constant velocity.
The graph is a curve that approaches infinite velocity.