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3 years ago

Calculate the average speed of a toy car that travels 20m in 40s

Physics

2 answers:

Roman55 [17]3 years ago

5 0

Answer:

2 per s

Explanation:

divid 40 and 20 it gives you = 2

lesya [120]3 years ago

4 0

Answer:

2m in 4s

Explanation:

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Please help fast

vaieri [72.5K]

D.sound insulators prevent from being transmitted better than elastic solids

Explanation:

The correct option from the given choices is that, sound insulators prevent sound from being transmitted better than elastic solids.

Sound is a form of wave that transmits energy from one point to another.

This wave form is a longitudinal wave in nature.

During the propagation of sound, it requires a material medium to move.

Sound insulators are special materials designed not to transmit sound energy.

Such materials cuts off sound. They are better than elastic solids in preventing sound transmission.

learn more:

Sound wave brainly.com/question/3619541

#learnwithBrainly

8 0

3 years ago

A tradesman sharpens a knife by pushing it with a constant force against the rim of a grindstone. The 30-cm-diameter stone is sp

Lorico [155]

Answer:

a. 0.21 rad/s2

b. 2.205 N

Explanation:

We convert from rpm to rad/s knowing that each revolution has 2π radians and each minute is 60 seconds

200 rpm = 200 * 2π / 60 = 21 rad/s

180 rpm = 180 * 2π / 60 = 18.85 rad/s

r = d/2 = 30cm / 2 = 15 cm = 0.15 m

a)So if the angular speed decreases steadily (at a constant rate) from 21 rad/s to 18.85 rad/s within 10s then the angular acceleration is

$\alpha = \frac{\Delta \omega}{\Delta t} = \frac{21 - 18.85}{10} = 0.21 rad/s^2$

b) Assume the grind stone is a solid disk, its moment of inertia is

$I = mR^2/2$

Where m = 28 kg is the disk mass and R = 0.15 m is the radius of the disk.

$I = 28*0.15^2/2 = 0.315 kgm^2$

So the friction torque is

$T_f = I\alpha = 0.315*0.21 = 0.06615 Nm$

The friction force is

$F_f = T_f/R = 0.06615 / 0.15 = 0.441 N$

Since the friction coefficient is 0.2, we can calculate the normal force that is used to press the knife against the stone

$N = F_f/\mu = 0.441/0.2 = 2.205 N$

7 0

3 years ago

What is the American psychology Association ethical principle of psychology and code of conduct based upon

solmaris [256]

The correct answer is B

4 0

3 years ago

Frame S' passes frame S in the usual way (positive directions). An object also moves in the positive direction. Which is true? T

lisov135 [29]

Answer:

The answer is "The object's speed relative to S can be greater than or less than its speed relative to S', depending on the actual values."

Explanation:

The S' frame and the object are moving in a positive direction. The object is moving with respect to the S frame so the S frame the rest frame

take the velocity of the object with respect to the rest frame as v and the velocity of the S' frame with respect S frame as v2

relative velocity of the object to the S' frame would be

Vrel = v2- v

This means the Vrel of the object with respect to the S' frame is less than the Vrel of the object with respect to the S frame

However is the S' velocity is greater than that of the object then the Vrel of the object with respect to the S' frame is greater than the Vrel of the object with respect to the S frame.

This would mean the second option is the answer, the relative speed of the object depends on the actual values.

3 0

3 years ago

Physicists often measure the momentum of subatomic particles moving near the speed of light in units of MeV/c, where c is the sp

maxonik [38]

Answer:

kg m/s

Explanation:

e = Charge = C

V = Voltage = $\dfrac{N}{C}m$

c = Speed of light = m/s

Momentum is given by

$\dfrac{MeV}{c}=\dfrac{e\times V}{c}\\\Rightarrow \dfrac{MeV}{c}=\dfrac{C\times \dfrac{N}{C}\times m}{m/s}\\\Rightarrow \dfrac{MeV}{c}=Ns\\\Rightarrow \dfrac{MeV}{c}=kg\times \dfrac{m}{s}\times s\\\Rightarrow \dfrac{MeV}{c}=kg\cdot m/s$

The unit of MeV/c in SI fundamental units is kg m/s

5 0

3 years ago