Velocity function, unit vector notation, acceleration, speed

In summary, the problem involves finding the acceleration and speed of a particle given its velocity function in vector notation. The rules of differentiation can be applied to find the acceleration, which is the derivative of the velocity function. The speed can be found by taking the magnitude of the velocity vector. The acceleration can be zero when the derivatives of the functions in the velocity vector are equal to zero.
  • #1
ColtonCM
33
2
The problem:

The velocity ~v (vector notation, don't know how to type) is given by:

~v = (6.0t - 4.0t^2)ˆi + 8.0ˆj + (3.0t) with |~v| in meters per second and positive t seconds. ˆi, ˆj, ˆk have their usual meanings (unit vector notation).

(a) What is the acceleration ~a of the particle when t = 3.0 s?
(b) What is the speed of the particle |~v| at t = 3.0 s?
(c) If ever, when would the acceleration of the particle ~a be zero m/s^2?

I know what unit vector notation is and I know that acceleration is the derivative of velocity function and I know how to do the Calculus to obtain those things, but I don't know how what this function is when applied with unit vector notation? i refers to x-axis, j to y-axis, and k to z-axis. Am I allowed to take the derivative of each function to obtain acceleration, do I combine the functions, or in other words how do I handle this question?

Thanks for your time,

Colton Casados-Medve
 
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  • #2
The rules of differentiation hold: the derivative of a sum is the sum of the derivatives, and the derivative of a function multiplied by a constant is the derivative multiplied by the constant. The unit vectors along the axes x, y, z are constants. If ##\vec V = X(t) \hat x + Y(t) \hat y + Z(t) \hat z ##
## \frac{d \vec V}{dt} = \frac{dX(t)}{dt} \hat x+ \frac{dY(t)}{dt} \hat y+ \frac{dZ(t)}{dt} \hat z ##
 
  • #3
ehild said:
The rules of differentiation hold: the derivative of a sum is the sum of the derivatives, and the derivative of a function multiplied by a constant is the derivative multiplied by the constant. The unit vectors along the axes x, y, z are constants. If ##\vec V = X(t) \hat x + Y(t) \hat y + Z(t) \hat z ##
## \frac{d \vec V}{dt} = \frac{dX(t)}{dt} \hat x+ \frac{dY(t)}{dt} \hat y+ \frac{dZ(t)}{dt} \hat z ##

Got it, thanks a lot!
 

1. What is a velocity function?

A velocity function is a mathematical representation of an object's velocity at any given time. It is often denoted by v(t) or ẋ(t) and is typically expressed in terms of distance and time.

2. How is unit vector notation used in physics?

Unit vector notation is used to represent the direction of a vector in three-dimensional space. It is denoted by placing a unit vector (i, j, or k) in front of the magnitude of the vector. This notation is particularly useful in physics because it allows for easy calculation of vector quantities such as velocity, acceleration, and force.

3. What is acceleration?

Acceleration is the rate of change of an object's velocity over time. It is a vector quantity, meaning it has both magnitude and direction. In other words, it describes how an object's velocity is changing and in which direction it is changing.

4. How is speed different from velocity?

Speed and velocity are often used interchangeably, but they actually have different meanings. Speed is a scalar quantity that describes how fast an object is moving, regardless of its direction. Velocity, on the other hand, is a vector quantity that includes both the speed and direction of an object's motion.

5. What is the difference between average and instantaneous velocity?

Average velocity is the total displacement of an object divided by the total time it takes to travel that distance. It gives an overall picture of an object's motion. Instantaneous velocity, on the other hand, is the velocity of an object at a specific moment in time. It is calculated by taking the derivative of the position function with respect to time.

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