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Salsk061 [2.6K]
3 years ago
13

A student stays at her initial position for a bit of time, then walks slowly in a straight line for a while, then stops to rest

a while, and finally runs quickly back to her initial position along a straight line. Which of the following statements is true about the average speed and the magnitude of the average velocity of the student during her trip? Her average speed is greater than the magnitude of her average velocity. Her average speed is the same as the magnitude of her average velocity. Her average speed is less than the magnitude of her average velocity. The student's average speed and velocity cannot be compared without knowing the farthest point she reached.
Physics
1 answer:
IRINA_888 [86]3 years ago
5 0

Answer:Average speed is greater than average velocity.

Explanation  :

Given

student walks slowly along a straight line for a while ,then stops to rest a while, and finally runs quickly back to her initial position

Let x be the length of track and the whole process takes t time

For average speed =\frac{distance\ traveled}{time\ taken}

Average speed=\frac{2x}{t}

For average velocity =\frac{Displacement}{time\ taken}

Since displacement is zero as she returns to its initial position.

Average velocity=0

Therefore Average speed is greater than average velocity.

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A single loop of wire with an area of 0.0780 m2 is in a uniform magnetic field that has an initial value of 3.80 T, is perpendic
Katarina [22]

Answer:

The induced current is 26.7 mA

Explanation:

Given;

area of the loop, A = 0.078 m²

initial magnetic field, B₁ = 3.8 T

change in the magnetic field strength, dB/dt = 0.24 T/s

The induced emf is calculated as;

emf = - \frac{d \phi}{dt} \\\\emf = -\frac{dB.A}{dt} \\\\emf = A (\frac{dB}{dt} )\\\\emf = 0.078(0.24)\\\\emf = 0.0187 \ V

The resistance of the loop = 0.7 Ω

The induced current is calculated as;

V = IR\\\\I = \frac{V}{R} = \frac{emf}{R} = \frac{0.0187}{0.7} = 0.0267 \ A = 26.7 \ mA

4 0
2 years ago
The drag force on a falling coffee filter can be modeled as a linear function with respect to velocity, F⃗ D =−bv, where b is a
nordsb [41]

Newton's second law and graphical analysis allow us to find the correct answer for the measure of the constant b is:

    D) Stack several filters to change the mass measure the acceleration of the system.

Newton's second law establishes a relationship between the net force, the mass and the acceleration of the bodies.  

         ∑ F = m a

Where the bold letters indicate vectors, F is the force, m the mass and the acceleration of the body.

They indicate that the drag force on the filters is

         F = - b v

Where b is a positive constant that depends on the shape and area of ​​the filter and v is the speed of the filter.

Let's write Newton's second law.

         W - fr  = ma

         W -bv  = ma

         

In the experiment the students indicate that they can measure the position, velocity and acceleration of the body.

Based on the above, if we place several filter weights and measure their speed and acceleration in each case, we can make a graph of velocity versus acceleration, we can take the value of the constant b from the slope.

Let's analyze the different answers:

A) False. The constant b depends on the shape of the filter therefore it must be kept constant.

B) False. The constant depends on the area, so it must be kept constant.

C) May be. In this case, since we have the terminal velocity, the acceleration is zero, Newton's second law remains.

                    B v - W = 0

                    b = \frac{W}{v}  

The problem with the method is the difficulty of measuring the compression terminal velocity.

D) True. According to the discussion of the velocity versus acceleration. graph, the constant b is equal to the slope of the graph.

E) May be. The problem with this method is finding a reliable value for the terminal velocity.

In conclusion, using Newton's second law and graphical analysis we can find the correct answer for the measure of the constant b is:

 D) Stack several filters to change the mass measure the acceleration of the system.

Learn more here:  brainly.com/question/2441565

6 0
2 years ago
The Back Saver Sit and Reach from the Fitnessgram measure this fitness component.
MAVERICK [17]
The correc answer is B.
7 0
3 years ago
A ball is dropped from a window and takes two seconds to reach the ground .it starts from rest and reaches a final speed of 20m/
Akimi4 [234]
The ball can't reach the speed of 20 m/s in two seconds, unless you THROW it down from the window with a little bit of initial speed. If you just drop it, then the highest speed it can have after two seconds is 19.6 m/s .

If an object starts from rest and its speed after 2 seconds is 20 m/s, then its acceleration is 20/2 = 10 m/s^2 .

(Gravity on Earth is only 9.8 m/s^2.)
3 0
3 years ago
scientific endeavor should only be pursued after known tradeoffs associated with the research have been considered. True or Fals
AfilCa [17]
This is false. There were many times in history when people discovered something that they didn't even know was possible or didn't even plan to discover it. Knowing tradeoffs doesn't mean that something won't surprise you or that all will go according to plan.
8 0
3 years ago
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