Vectors and motion in 2D (physics problem)

In summary, the conversation is discussing the topic of vectors and motion in 2D, specifically in relation to the bacterium Escherichia coli. The bacterium is known to swim in a zig-zag pattern at a constant speed of 20 micrometers, and the figure provided shows its trajectory from point A to point E. The conversation then poses three questions: calculating the x and y components of velocity for each segment, finding the total distance traveled and magnitude of net displacement, and determining the bacterium's average velocity and direction for the entire trip.
  • #1
natty210
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vectors and motion in 2D (physics 1111 problem!)

The bacterium Escherichia coli (or E. coli) is a single-celled organism that lives in the gut of healthy humans and animals. When grown in a uniform medium rich in salts and amino acids, these bacteria swim along zig-zag paths at a constant speed of 20[tex]\mu[/tex]m. The figure shows the trajectory of an E. coli as it moves from point A to point E. Each segment of the motion can be identified by two letters, such as segment BC.

(graph is attached!)***

a) for each of the four segments in the bacterium's trajectory, calculate the x and y components of its velocity

b) calculate both the total distance traveled and the magnitude of the net displacement for the entire motion.

c) what are the magnitude and the direction of the bacterium's average velocity and for the entire trip?
 

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  • #2
Welcome to PF!

Hi natty210! Welcome to PF! :wink:

Show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
 
  • #3


I would approach this problem by first identifying the given information and variables. In this case, we are dealing with motion in 2D, specifically the movement of the bacterium E. coli. The given speed for the bacterium is 20 micrometers per second and the trajectory is represented by a zig-zag path from point A to point E.

a) To calculate the x and y components of the bacterium's velocity, we can use the formula v = d/t, where v is the velocity, d is the distance traveled, and t is the time taken. Since the bacterium is moving at a constant speed, we can assume that the time taken for each segment is the same. Therefore, for segment AB, the velocity components would be 20\mum/s in the x-direction and 0\mum/s in the y-direction. For segment BC, the velocity components would be 10\mum/s in the x-direction and 10\mum/s in the y-direction. Similarly, for segments CD and DE, the velocity components would be 20\mum/s and 0\mum/s respectively in the x-direction, and 0\mum/s and -20\mum/s respectively in the y-direction.

b) The total distance traveled by the bacterium can be calculated by adding up the distances traveled in each segment. In this case, it would be 20\mum + 20\mum + 20\mum + 20\mum = 80\mum. The magnitude of the net displacement can be calculated using the Pythagorean theorem, which would be the square root of the sum of the squares of the x and y displacements. In this case, it would be sqrt((20\mum)^2 + (-20\mum)^2) = 28.28\mum.

c) The magnitude of the bacterium's average velocity can be calculated by dividing the total distance traveled by the total time taken. Since the time taken for each segment is the same, we can use the formula v_avg = d/t. In this case, it would be 80\mum/4s = 20\mum/s. The direction of the average velocity can be determined by considering the net displacement. In this case, the bacterium moved 20\mum in the x-direction and -20\
 

1. What is a vector in physics?

A vector in physics is a quantity that has both magnitude and direction. It is typically represented by an arrow, with the length of the arrow representing the magnitude and the direction of the arrow indicating the direction. Examples of vectors include displacement, velocity, and acceleration.

2. How do you calculate the magnitude of a vector?

The magnitude of a vector can be calculated using the Pythagorean theorem, where the magnitude is equal to the square root of the sum of the squares of the components of the vector. Alternatively, if the vector is represented by its components in the x and y directions, the magnitude can be calculated using the formula: magnitude = √(x^2 + y^2).

3. What is the difference between distance and displacement?

Distance is a scalar quantity that refers to the total length of the path traveled by an object, while displacement is a vector quantity that refers to the straight-line distance between the initial and final positions of an object. In other words, displacement takes into account the direction of an object's movement, while distance does not.

4. How do you calculate the average velocity of an object?

The average velocity of an object can be calculated by dividing the displacement of the object by the time it took to travel that distance. This can be represented by the formula: average velocity = displacement / time.

5. What is projectile motion?

Projectile motion refers to the motion of an object that is launched into the air and then moves under the influence of gravity. It follows a curved path called a parabola due to the combination of its horizontal and vertical velocities. The horizontal velocity remains constant, while the vertical velocity changes due to the acceleration of gravity.

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