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3 years ago

True or False. The more energy put into making a sound the lower its intensity.

Physics

2 answers:

il63 [147K]3 years ago

7 0

The answer is true the more energy put into making a sound the lower it’s density.

Aleks04 [339]3 years ago

5 0

The answer is true I did that test befor

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A plane mirror and a concave mirror (f = 8.40cm) are facing each other and are separated by a distance of 22.0 cm. An object is

lesya [120]

Answer:

The distance of the image produced by the concave mirror is 11.27 cm.

Explanation:

Given that,

Focal length = 8.40 cm

Distance between object and plane mirror = 11.0 cm

Distance between plane mirror and concave mirror = 22.0 cm

We need to calculate the object distance

$u =11.0+22.0 = 33.0\ cm$

We need to calculate the distance of the image

Using formula of distance of the image

$v=\dfrac{uf}{u-f}$

Where, u = Object distance

f = focal length

Put the value into the formula

$v=\dfrac{33.0\times8.40}{33.0-8.40}$

$v=11.27\ cm$

Hence, The distance of the image produced by the concave mirror is 11.27 cm.

4 0

3 years ago

The transmission of heat requiring the movement of a liquid or a gas is

AysviL [449]

Answer:

convection

Explanation:

7 0

4 years ago

A car of mass 960 kg is free-wheeling down an incline at a constant speed of 9.0 m s–1.

Orlov [11]

Need to draw it first.....
but there is no option here to draw .. why?
anyway , here the car is going with a uniform velocity..
so the acceleration of the car=0, a=0
so resistive force on the car=component along the inclined plane of the weight of the car=mg*cos(90-15)=960*9.8*cos 75=?

4 0

4 years ago

a railroad tie weights 920 N and is 2.6 m long. How much force is required to: pick it up off the ground? lift one end and rotat

lukranit [14]

1) The minimum force needed is 920 N

2) The minimum force is 460 N

3) The minimum force is 598 N

Explanation:

We can answer this part by simply looking at the forces involved. In fact, there are two forces acting on the railroad:

Its weight, W, acting downward
The force applied to lift it, F, upward

So the net force on the railroad is

$\sum F = F - W$

where

W = 920 N is the weight of the railroad

In order to lift the railroad, the net force must be upward, so

$\sum F \geq 0$

And therefore

$F\geq W$

which means that the minimum force needed is equal to the weight of the railroad, 920 N.

In this case, we have to use the principle of equilibrium of moments.

In fact, when the railroad rotates uniformly (=constant angular speed) about its end, it means that the moment produced by the weight (acting in one direction) is equal to the moment produced by the force applied (acting in the other direction). Therefore, we can write:

$W \frac{L}{2} = F L$

where

W = 920 N is the weight

L = 2.6 m is the length of the railroad

F is the force applied

We wrote L/2 on the left of the equation because the weight acts at the center of mass of the railroad (located at the midpoint), while on the right it is L because the force F is applied at the end of the railroad.

Solving for F,

$F=\frac{W}{2}=\frac{920}{2}=460 N$

This problem is similar to the previous part, however in this case, the force applied F is applied 0.6 m from the end, pivoting around the opposite end.

This means that the distance between the point of application of the force F and the pivot is

L' = L - 0.6

where

L = 2.6 m

Therefore the equation for the equilibrium of moments becomes

$W\frac{L}{2}=F(L-0.6)$