Math Problem Statement

The figure shows the force acting on a 1.0 kg object as it moves along the x-axis. The object is at rest at the origin at t = 0 s. What are its acceleration and velocity at t = 6 s?

The figure shows the force acting on a 1.0 kg object as it moves along the x-axis. The object is at rest at the origin at t = 0 s. What are its acceleration and velocity at t = 6 s?

Solution

To solve for the acceleration and velocity of the object at t=6st = 6 \, \text{s}, let's go through the steps systematically using the given force-time graph:

1. Mass of the Object

The mass of the object is given as m=1.0kgm = 1.0 \, \text{kg}.

2. Newton’s Second Law of Motion

We know from Newton's second law that: F=maF = m a This can be rewritten as: a=Fma = \frac{F}{m} Thus, for each interval, we will find the acceleration by dividing the force by the mass.

3. Calculating Acceleration in Each Time Interval

The force is given as a step function in the graph, so the force acting on the object varies with time. The time intervals and corresponding forces are:

  • From t=0st = 0 \, \text{s} to t=2st = 2 \, \text{s}, Fx=4NF_x = 4 \, \text{N}
  • From t=2st = 2 \, \text{s} to t=4st = 4 \, \text{s}, Fx=0NF_x = 0 \, \text{N}
  • From t=4st = 4 \, \text{s} to t=6st = 6 \, \text{s}, Fx=2NF_x = -2 \, \text{N}

Using a=Fma = \frac{F}{m}, let's compute the acceleration in each interval:

  • For t=0st = 0 \, \text{s} to t=2st = 2 \, \text{s}, a=41.0=4m/s2a = \frac{4}{1.0} = 4 \, \text{m/s}^2
  • For t=2st = 2 \, \text{s} to t=4st = 4 \, \text{s}, a=01.0=0m/s2a = \frac{0}{1.0} = 0 \, \text{m/s}^2
  • For t=4st = 4 \, \text{s} to t=6st = 6 \, \text{s}, a=21.0=2m/s2a = \frac{-2}{1.0} = -2 \, \text{m/s}^2

4. Velocity Calculations

The object is initially at rest at t=0st = 0 \, \text{s}, so v0=0m/sv_0 = 0 \, \text{m/s}. Now, we can calculate the velocity after each time interval.

  • From t=0st = 0 \, \text{s} to t=2st = 2 \, \text{s}: v=v0+aΔt=0+4×2=8m/sv = v_0 + a \Delta t = 0 + 4 \times 2 = 8 \, \text{m/s} So, at t=2st = 2 \, \text{s}, the velocity is 8m/s8 \, \text{m/s}.

  • From t=2st = 2 \, \text{s} to t=4st = 4 \, \text{s}: Since the acceleration is zero in this interval, the velocity remains constant: v=8m/sv = 8 \, \text{m/s} So, at t=4st = 4 \, \text{s}, the velocity is still 8m/s8 \, \text{m/s}.

  • From t=4st = 4 \, \text{s} to t=6st = 6 \, \text{s}: The acceleration is 2m/s2-2 \, \text{m/s}^2, so the velocity change is: v=8+(2×2)=84=4m/sv = 8 + (-2 \times 2) = 8 - 4 = 4 \, \text{m/s} Thus, at t=6st = 6 \, \text{s}, the velocity is 4m/s4 \, \text{m/s}.

5. Summary of Results

  • Acceleration at t=6st = 6 \, \text{s}: a=2m/s2a = -2 \, \text{m/s}^2
  • Velocity at t=6st = 6 \, \text{s}: v=4m/sv = 4 \, \text{m/s}

Would you like more details or have any questions on the solution?

Here are 5 related questions for further exploration:

  1. What would the position of the object be at t=6st = 6 \, \text{s}?
  2. How would the velocity change if the mass were different?
  3. What is the net work done on the object by the force over the time period?
  4. Can we calculate the impulse experienced by the object during the first 2 seconds?
  5. How does changing the direction of force after t=4st = 4 \, \text{s} affect the motion?

Tip: When calculating velocity, it's important to account for each time interval separately if the force acting on the object changes.

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Math Problem Analysis

Mathematical Concepts

Newton's Second Law
Kinematics

Formulas

Newton's Second Law: F = ma
Acceleration: a = F/m
Velocity: v = v0 + aΔt

Theorems

Newton's Second Law

Suitable Grade Level

Grades 10-12