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4 years ago

A constant net force acts on an object. which of the following best describes the object's motion?

1 answer:

4 0

The object is moving with a decreasing acceleration. The object is moving with a constant velocity.

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A negative test charge experiences a force to the right as a result of an electric field. Which is the best conclusion to draw

zaharov [31]

Answer:

The electric field points to the left because the force on a negative charge is opposite to the direction of the field.

Explanation:

In an electric field, a positive charge has tendency to move from high to low potential and hence experience the electric force in the direction of electric field since electric field lines are directed from high to low potential.

In an electric field, a negative charge has tendency to move from low to high potential and hence experience the electric force in the direction opposite to electric field since electric field lines are directed from high to low potential.This phenomenon happened because The electric field from a positive charge will points away from the charge while the electric field from a negative charge will points toward the charge.

7 0

3 years ago

A poker is a stiff, nonflammable rod used to push burning logs around in a fireplace. for safety and comfort of use, the poker s

Valentin [98]

Answer: The poker stick should have low thermal conductivity and high specific heat.

Explanation: For a poker stick that is non flammable, it should have some properties which will not let it heat up faster.

Two properties that satisfy the poker stick are:

Specific heat
Thermal conductivity

Specific heat is defined as the amount of heat require to raise the temperature of a mass M by 1 °C. More the specific heat, more amount of heat will be required to raise the temperature of a substance.

Thermal conductivity is defined as the ability of a substance to conduct heat. More thermal conductivity means that the substance will get hot faster as it will conduct more amount of heat.

So, for a substance that should not conduct more heat like the poker stick must have high specific heat and low thermal conductivity.

6 0

4 years ago

A rectangular key was used in a pulley connected to a line shaft with a power of 7.46 kW at a speed of 1200 rpm. If the shearing

Damm [24]

Given:

Shaft Power, P = 7.46 kW = 7460 W

Speed, N = 1200 rpm

Shearing stress of shaft, $\tau _{shaft}$ = 30 MPa

Shearing stress of key, $\tau _{key}$ = 240 MPa

width of key, w = $\frac{d}{4}$

d is shaft diameter

Solution:

Torque, T = $\frac{P}{\omega }$

where,

$\omega = \frac{2\pi N}{60}$

$T = \frac{7460}{\frac{2\pi (1200 )}{60}}$ = 59.365 N-m

Now,

$\tau _{shaft} = \tau _{max} = \frac{2T}{\pi (\frac{d}{2})^{3}}$

$30\times 10^{6} = \frac{2\times 59.365}{\pi (\frac{d}{2})^{3}}$

d = 0.0216 m

Now,

w = $\frac{d}{4}$ = $\frac{0.02116}{4}$ = 5.4 mm

Now, for shear stress in key

$\tau _{key}$ = $\frac{F}{wl}$

we know that

T = $F \times r$ = F. $\frac{d}{2}$

⇒ $\tau _{key}$ = $\frac{\frac{T}{\frac{d}{2}}}{wl}$

⇒ $240\times 10^{6}$ = $\frac{\frac{59.365}{\frac{0.0216}{2}}}{0.054l}$

length of the rectangular key, l = 4.078 mm

7 0

3 years ago

Read 2 more answers

If you install special sound-reflecting windows that reduce the sound intensity level by 30.0 db , by what factor have you reduc

shusha [124]

Answer: The sound intensity was reduced by -14.77 dB.

Explanation:

The level of the intensity of the sound with respect to the reference value is called Sound Intensity level.

$L_I=10\log\frac{I}{I_o} dB$

I = Intensity of the sound

$I_o$ = Reference sound intensity

According to question, sound-reflecting windows that reduce the sound intensity level by 30.0 db .

Let the intensity of the sound be $I_o$ and reduced intensity be I.

$I=\frac{I_o}{30} dB$

$L_I=10\log\frac{I}{I_o} dB$

$L_I=10\log\frac{\frac{I_o}{30}}{I_o}=10\log\frac{1}{30} dB=-14.77 dB$

The sound intensity was reduced by -14.77 dB.

3 0

3 years ago

Two cars A and B are moving with velocities 20 m/s and 15 m/s in the direction east and west respectively. If

Sphinxa [80]

Answer:

Distance between them is 4,200 meters.

Explanation:

Consinder car A:

${ \bf{distance = speed \times time }}$

substitute:

$distance = 20 \times (2 \times 60) \\ = 2400 \: m$

Consider car B:

$distance = 15 \times (2 \times 60) \\ = 1800 \: m$

since these cars move in opposite directions, distance between them is their summation:

$distance \: between = { \sum(distance \: of \: each \: car)} \\ = 2400 + 1800 \\ = 4200 \: m$

3 0

3 years ago