Finding Displacement and Velocity at a Given Time

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In summary, the task is to find the expression for the velocity and the value of displacement and velocity at t=5 for two given functions, s(t) = 3t + 7 and s(t) = t^3 - 2t^2 + 4t - 1. Using the given functions and plugging in t=5, the displacement is found to be 22 m/s for s(t) = 3t + 7 and 94 m/s for s(t) = t^3 - 2t^2 + 4t - 1. However, the problem is asking for both displacement and velocity, and since only displacement was found, further steps are needed to find the velocity at
  • #1
MiniOreo1998
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Homework Statement


For each function, find an expression for the velocity and the value of the displacement and velocity at t=5. Displacement is in metres and time is in seconds.

Homework Equations


A)[/B] s(t) = 3t + 7

B) s(t) = t3 - 2t2 + 4t - 1

The Attempt at a Solution



A) [/B]s(t) = 3t + 7
s(5) = 3(5) + 7
= 22 m/s

B) s(t) = t3 - 2t2 + 4t - 1
s(5) = 53 - 2(5) + 4(5) - 1
=94 m/s

 
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  • #2
MiniOreo1998 said:

Homework Statement


For each function, find an expression for the velocity and the value of the displacement and velocity at t=5. Displacement is in metres and time is in seconds.

Homework Equations


A)[/B] s(t) = 3t + 7

B) s(t) = t3 - 2t2 + 4t - 1

The Attempt at a Solution



A) [/B]s(t) = 3t + 7
s(5) = 3(5) + 7
= 22 m/s

B) s(t) = t3 - 2t2 + 4t - 1
s(5) = 53 - 2(5) + 4(5) - 1
=94 m/s
s usually denotes position or displacement, not velocity. How do you find velocity from displacement?

Remember, the problem is asking you to find both displacement and velocity at a given time, t.

Hint: You posted this problem in the Calculus HW forum, yet you used no calculus. Didn't you find that a little odd?
 

1. What is the difference between velocity and displacement?

Velocity is a vector quantity that refers to the rate of change of an object's position with respect to time. It includes both the magnitude and direction of the object's motion. Displacement, on the other hand, is a vector quantity that refers to the change in an object's position in a specific direction. It does not take into account the object's path or the time taken to cover the distance.

2. How is velocity calculated?

Velocity is calculated by dividing the change in an object's position (displacement) by the time taken to cover that change. In other words, velocity equals displacement divided by time. The SI unit for velocity is meters per second (m/s).

3. Can velocity be negative?

Yes, velocity can be negative. This indicates that the object is moving in the opposite direction of the chosen positive direction. For example, if an object is moving east with a velocity of +10 m/s, and then starts moving west with a velocity of -10 m/s, the change in direction results in a negative velocity.

4. How does displacement relate to velocity?

Displacement is a measure of the total change in an object's position, while velocity is a measure of the rate of change of an object's position. In other words, velocity is the derivative of displacement with respect to time.

5. Can an object have a constant velocity but changing displacement?

Yes, an object can have a constant velocity but changing displacement. This occurs when the object is moving in a straight line at a constant speed. Although the velocity remains the same, the displacement is constantly increasing as the object continues to move forward.

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