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Masja [62]
3 years ago
15

1. Which of the following is not an example of friction?

Physics
1 answer:
mario62 [17]3 years ago
8 0

ueirudjrufu rhfyrhfy. fur dhrbrhfbf

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A 0.91 kg ball and a 2 kg ball are connected by a 0.95 m long rigid, massless rod. The rod is rotating clockwise about its cente
Sloan [31]

Answer: 0.235

Explanation:

Given data.

M1 = 0.91 Kg

M2 = 2kg

L = 0.95m

N = 35rpm

t = 10.44secs

Solution:

• we first solve for the center of gravity

•we calculate our moment of inertia

• we calculate the angular velocity

• we solve for our torque ( t )

6 0
2 years ago
A soccer ball of mass 0.4 kg is moving horizontally with a speed of 20 m/s when it is kicked by a player. The kicking force is s
amid [387]

Answer:

v_{f} = 74 m/s, F = 230 N

Explanation:

We can work on this exercise using the relationship between momentum and moment

        I = ∫ F dt = Δp

bold indicates vectors

we can write this equations in its components

X axis

       Fₓ t = m ( -v_{xo})

Y axis  

        t = m (v_{yf} - v_{yo})

in this case with the ball it travels horizontally v_{yo} = 0

Let's use trigonometry to write the final velocities and the force

        sin 30 = v_{yf} / vf

        cos 30 = v_{xf} / vf

        v_{yf} = vf sin 30

        v_{xf} = vf cos 30

         sin40 = F_{y} / F

         F_{y} = F sin 40

         cos 40 = Fₓ / F

         Fₓ = F cos 40

let's substitute

      F cos 40 t = m ( cos 30 - vₓ₀)

      F sin 40 t = m (v_{f} sin 30-0)

we have two equations and two unknowns, so the system can be solved

        F cos 40 0.1 = 0.4 (v_{f} cos 30 - 20)

        F sin 40 0.1 = 0.4 v_{f} sin 30

we clear fen the second equation and subtitles in the first

         F = 4 sin30 /sin40     v_{f}

         F = 3.111 v_{f}

        (3,111 v_{f}) cos 40 = 4 v_{f} cos 30 - 80

        v_{f} (3,111 cos 40 -4 cos30) = - 80

        v_{f} (- 1.0812) = - 80

        v_{f} = 73.99

        v_{f} = 74 m/s

now we can calculate the force

          F = 3.111 73.99

          F = 230 N

6 0
3 years ago
14) A race car accelerates from rest to a velocity of 41 m/s in 480 m. What is the acceleration of the race car?
natka813 [3]

Answer:

Explanation:

V₀ = 0 m/s

V = 41 m/s

S = 480 m

___________

a - ?

Distance traveled:

S =  (V² - V₀²) / (2*a)

Acceleration :

a = (V² - V₀²) / (2*S)

a = (41² - 0²) / (2*480) = 1.75 m/s²

8 0
1 year ago
Plzzzzzzzzzz!!!!!!! Hurryyyyy
Scilla [17]

Answer:

student  A or B

Explanation:

A common demonstration is to put a ringing alarm clock or bell in the bell jar, and when the vacuum is created, you can no longer hear the sound of the clock/bell.

The bell is connected to a lab pack or batteries and rung to show pupils it can be heard under normal circumstances. The bell jar is then connected to a vacuum pump using a vacuum plate (see Fig 2) and the air is removed from inside creating a near vacuum. The bell is then again rung. This time however, it cannot be heard.

Small low voltage buzzers can be used as a bell replacement for the bell and work in exactly the same way though teachers generally prefer bells as students may be able to see the hammer moving, proving that it is actually ringing even though they cannot hear it.

Some vacuum pumps are better than others at keeping a strong vacuum though if you cannot completely lose the sound, you will at least notice the volume decreasing.

Sound is simply a series of longitudinal waves travelling from the source, through the air to our ears. Without air present, these waves cannot form and therefore sound cannot be conveyed.

In a longitudinal wave the particles oscillate back and forth in the direction of the wave movement unlike transverse waves which like waves on the sea, single particles travel up and down and not in the direction of the wave.

Because you will not be able to create a perfect vacuum, you may still be able to hear the bell ring slightly. Vibrations from the ringing bell can also travel up to the bung in the bell jar which in turn may resonate the jar slightly. This means you may hear the bell ring, however strong the vacuum. To compensate for this, try to insulate the bell as much as possible from the bell jar. Hanging the bell using elastic cord means some of the vibrations will be absorbed by the cord and not be transferred to the bell jar.

3 0
2 years ago
Select the correct answer.<br> Which hand is negatively charged?
ozzi

Answer:

b

Explanation:

6 0
3 years ago
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