A particle of mass m is at rest at the origin at time t = 0. It is subjected to a force F (t) = F0e–bt in the x direction. Its speed v(t) is depicted by which of the following curves?
We are given a force that varies with time: . Since the particle starts from rest at the origin, its initial velocity is zero. According to Newton's second law, the acceleration is given by .
The velocity is the integral of acceleration with respect to time. Let's compute it step by step.
Step 1: Set up the integral for velocity.
Since the particle starts from rest, . Therefore,
Step 2: Evaluate the integral.
The integral of with respect to is . So,
Step 3: Analyze the behavior of .
The velocity function is .
Step 4: Compare with the given curves.
The correct curve must start at the origin (0,0), increase, and approach a horizontal asymptote (a constant value) as time increases. It should not decrease, oscillate, or have any discontinuities.
Final Answer: The curve that depicts this behavior is the one that starts at the origin and increases, approaching a constant value asymptotically. Based on the typical representation of such functions, it is likely the first option (top-left image) if it shows a curve starting at (0,0) and leveling off.
Newton's Second Law: or for one-dimensional motion.
Velocity from Acceleration: . Here, and .
Exponential Decay: The force decays exponentially from to 0. The parameter determines the rate of decay.