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3 years ago

If a girl is standing still and holding a box, is she doing any work? Why or why not?

2 answers:

7 0

I beleive she isnt doing any work due to holding the box motionless, you must be exerting a force in the direction of the box motion. If she is just standing there holding the box their isn't no work becuase no distance has been covered. work = force = distance.

lesantik [10]3 years ago

7 0

<span>W = F * d, and since d=0, therefore W=0.
(If you want to be mathematical about it.)
</span>

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Suppose a plot of inverse wavelength vs frequency has slope equal to 0.119, what is the speed of sound traveling in the tube to

strojnjashka [21]

Answer:

8.40 m/s

Explanation:

Slope of the plot is 0.119

Slope of a plot is given by the change in y direction divided by the change in x direction

Here, the y axis represents inverse wavelength and the x axis represents frequency.

f = Frequency (Hz, assumed)

v = Phase velocity (m/s, assumed)

λ = Wavelength (m, assumed)

So, slope

$m=\frac{\frac{1}{\lambda}}{f}$

Now,

$\lambda=\frac{v}{f}\\\Rightarrow \lambda^{-1}=\frac{f}{v}$

$\\\Rightarrow m=\frac{\frac{f}{v}}{f}\\\Rightarrow 0.119=\frac{1}{v}\\\Rightarrow v=\frac{1}{0.119}\\\Rightarrow v=8.40\ m/s$

The speed of sound travelling in the tube is 8.40 m/s

5 0

4 years ago

What is the % error in using g = 10.0 m/s^2? (Take the value ofg as 9.8 m/s^2)

Alenkasestr [34]

Answer:

So percentage error will be 2 %

Explanation:

We have given initial value of acceleration due to gravity $g=10m/sec^2$

And final value of acceleration due to gravity $g=9.8m/sec^2$

We have to find the percentage error

We know that percentage error is given by $percentage\ error=\frac{initial\ value-final\ value}{initial\ value}\times 100$

So $percentage\ error=\frac{10-9.8}{10}\times 100=2$ %

4 0

3 years ago

ich statement best describes the fundamental difference between spiral and elliptical galaxies? Spiral galaxies are more massive

Ahat [919]

Answer:

The oldest stars in spiral galaxies are younger than the oldest stars in elliptical galaxies.

Explanation:

Spiral galaxies have a greater star formation than elliptical galaxies, since the latter contain less gas and dust. Therefore, the rate of creation of new stars is lower in elliptical galaxies. These galaxies are dominated by old stars, with a long evolution. While the spiral galaxies have stars with a faster evolution.

8 0

3 years ago

Read 2 more answers

Before 1960, people believed that the maximum attainable coefficient of static friction for an automobile tire on a roadway was

Eduardwww [97]

Answer:

4.18

Explanation:

Givens

The car's initial velocity $v_{i}$ = 0 and covering a distance Δx = 1/4 mi = 402.336 m in a time interval t = 4.43 s.

Knowns

We know that the maximum static friction force is given by:

$f_{s_max} =$ μ_s*n (1)

Where μ_s is the coefficient of static friction and n is the normal force.

Calculations

(a) First, we calculate the acceleration needed to achieve this goal by substituting the given values into a proper kinematic equation as follows:

Δx= $v_{i} +\frac{1}{2} at^2$

a=41 m/s

This is the acceleration provided by the engine. Applying Newton's second law on the car, so in equilibrium, when the car is about to move, we find that:

$f_{y}=n-mg=0\\ n=mg\\f_{x}=F-f_{s,max} =0\\ f_{s,max}=F=ma\\$

Substituting (3) into (1), we get:

$f_{s,max}=$ μ_s*m*g

Equating this equation with (4), we get:

ma= μ_s*m*g

μ_s=a/g

=4.18

3 0

4 years ago

A metal ring 4.00 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpend

liq [111]

Answer:

a) 0.21N/C

b) counterclockwise

Explanation:

a) to find the magnitude of the electric field you can use the following formula:

$\int Eds=-\frac{\Delta \Phi_B}{\Delta t}=-\frac{\Delta AB}{\Delta t}$

A: area of the ring = pi*r^2

E: electric field

Ф_B: magnetic flux

In the line integral you can assume E as constant. Furthermore, you calculate the change in the magnetic flux by taking into account that the time interval is 1.12/0.21=5.33s. By replacing in the formula you obtain:

$\frac{\Delta \Phi_B}{\Delta t}=\frac{A(B_f-B_i)}{5.33s}=\frac{\pi(0.04m)^2(1.12T)}{5.33}=1.056*10^{-3}W/s$

$E\int ds=E(2\pi r)=1.056*10^{-3}W/s\\\\E=\frac{1.056*10^{-3}W/s}{\pi(0.04m)^2}=0.21\frac{N}{C}$

the magnitude if the induced electric field is 0.21N/C

b) By the Lenz's law you can conclude that the current has a direction in a counterclockwise

6 0

3 years ago