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3 years ago

Explain how magnets have an attractive force and repulsive force

1 answer:

7 0

The force between two parallel wires carrying currents in the same direction is attractive. It is repulsive if the currents are in opposite directions.

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A vacuum cleaner produces sound with a measured sound level of 75.0 dB. (a) What is the intensity of this sound in W/m2? W/m2 (b

jonny [76]

Answer:

Part a)

$I = 3.16 \times 10^{-5} W/m^2$

Part b)

$P_o = 0.162 Pa$

Explanation:

Part a)

Level of sound = 75 dB

now we know that

$L = 10 Log\frac{I}{I_0}$

here we know that

$I_0 = 10^{-12} W/m^2$

now we have

$75 = 10 Log(\frac{I}{10^{-12}})$

$I = 3.16 \times 10^{-5} W/m^2$

Part b)

Intensity of sound wave is given as

$I = \frac{1}{2}\rho A^2\omega^2 c$

here we know that

$A = \frac{P_o}{Bk}$

so we have

$I = \frac{1}{2}\rho(\frac{P_o}{Bk})^2\omega^2 c$

$I = \frac{1}{2}\rho P_o^2 \frac{c^3}{B^2}$

now we know

$\rho = 1.2 kg/m^3$

$c = 340 m/s$

$B = 1.4 \times 10^5 Pa$

now we have

$3.16 \times 10^{-5} = \frac{1}{2}(1.2)P_o^2\frac{340^3}{(1.4\times 10^5)^2}$

$P_o = 0.162 Pa$

5 0

3 years ago

Why is it important for engineers to design bumper cars safely

rosijanka [135]

Answer:

Cars have bumpers designed to protect the body of the car from minor damage during low-speed collisions. ... They will use the engineering design process to design and build bumpers to protect the main parts of their car from damage, and use their knowledge of Newton's third law to explain what they observe.

Explanation:

3 0

3 years ago

Read 2 more answers

A steel rod is pulled in tension with a stress that is less than the yield strength. The modulus of elasticity may be calculated

pshichka [43]

Answer:

B. Axial stress divided by axial strain

Explanation:

Elasticity:

It is the tendency of an object to deform along the axis when an opposing force is applied without facing permanent change in shape.

Plasticity:

When an object crosses the elasticity limit, it enters plasticity where the change due to stress is permanent and the object might even break.

Yield strength:

Yield strength is the point of maximum bearable stress that indicates the limit of elasticity.

Our case:

As the stress applied is less than the yield strength, the rod is still in the elasticity state and its modulus can be calculated.

Modulus of Elasticity = Stress along axis/Ratio of change in length to original length

Axial strain is basically the ratio of change in length to original length.

So, Modulus of Elasticity = Axial Stress/ Axial Strain

6 0

3 years ago

The tendency of an object to resist a change in its motion is called

Nikolay [14]

Answer:

inertia

Explanation:

4 0

2 years ago

What step did Mendel take to be sure that his pea plants did not self-pollinate?

Ipatiy [6.2K]

Answer:

it is made up of some theory

Explanation:

it is an artificial pollination

8 0

3 years ago