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Helga [31]
2 years ago
12

A sled having a certain initial speed on a horizontal surface comes to rest after traveling 10 m. If the coefficient of kinetic

friction between the object and the surface is 0.20, what was the initial speed of the object
Physics
1 answer:
sergiy2304 [10]2 years ago
5 0

Answer:

the initial speed of the object is 6.26 m/s

Explanation:

given information:

distance, s = 10 m

the coefficient of kinetic friction, μ = 0.2

we use the equation where the kinetic energy is equal to the friction force.

kinetic energy, KE = \frac{1}{2} mv^{2}

friction work,  W = F(friction) s

KE = W

\frac{1}{2} mv^{2} = F(friction) s

where, F(friction) = μ N, N is normal force (N = m g)

                            = μ m g

so,

\frac{1}{2} mv^{2} = μ m g s

\frac{1}{2} v^{2} = μ g s

v^{2} = 2 μ g s

  = 2 (0.2) (9.8) (10)

  = 39.2

hence,

v = \sqrt{3.92}

  = 6.26 m/s

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If no friction acts on a diver during a dive, then which of the following statements is true? A) The total mechanical energy of
EleoNora [17]
If no frictional work is considered, then the energy of the system (the driver at all positions is conserved.

Let
position 1 = initial height of the diver (h₁), together with the initial velocity (v₁).
position 2 = final height of the diver (h₂) and the final velocity (v₂).

The initial PE = mgh₁ and the initial KE  = (1/2)mv₁²
where g = acceleration due to gravity,
m = mass of the diver.
Similarly, the final PE and KE are respectively mgh₂ and (1/2)mv₂².
PE in position 1 is converted into KE due to the loss in height from position 1 to position 2.
 
Therefore
(KE + PE) ₁ = (KE + PE)₂

Evaluate the given answers.
A) The total mechanical energy of the system increases.
     FALSE

B) Potential energy can be converted into kinetic energy but not vice versa.
     TRUE

C) (KE + PE)beginning = (KE + PE) end.
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D) All of the above.
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4 0
2 years ago
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Mr. Chang's class participated in a science experiment where they placed three substances outside in the sunlight to determine w
Montano1993 [528]

Answer:

B or D but im pretty sure it is D

Explanation:

When molecules are left in the sun, it heats up. When molecules heat up, the begin to vibrate rapidly. The sun is not constant as it could get blocked by clouds, so it would, at times, slow down the movement of the molecules. The answer is most likely D.

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Cylinder A is moving downward with a velocity of 3 m/s when the brake is suddenly applied to the drum. Knowing that the cylinder
Xelga [282]

Answer:

Incomplete question

Check attachment for the given diagram

Explanation:

Given that,

Initial Velocity of drum

u=3m/s

Distance travelled before coming to rest is 6m

Since it comes to rest, then, the final velocity is 0m/s

v=3m/s

Using equation of motion to calculate the linear acceleration or tangential acceleration

v²=u²+2as

0²=3²+2×a×6

0=9+12a

12a=-9

Then, a=-9/12

a=-0.75m/s²

The negative sign shows that the cylinder is decelerating.

Then, a=0.75m/s²

So, using the relationship between linear acceleration and angular acceleration.

a=αr

Where

a is linear acceleration

α is angular acceleration

And r is radius

α=a/r

From the diagram r=250mm=0.25m

Then,

α=0.75/0.25

α =3rad/sec²

The angular acceleration is =3rad/s²

b. Time take to come to rest

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v=u+at

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The answers would be:

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If you'd like to know more about the different boundaries, read on:

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Transform boundaries occur when two plates slide against each other. They move slide side by side, so nothing is formed nor do they go under each other. Although, this type of boundaries create strong earthquakes.

Lastly, divergent boundaries occur when two plates move apart. The separation creates a way for magma to come up. New crust is formed when the magma that seeps out is cooled by its cooler surroundings. This is observed in the mid oceanic ridge.

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