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Nadya [2.5K]
3 years ago
15

a car moving on a road passes by kilometer 218 at 10:15 am and milestone 236 at 10:30 am. determine an average scalar speed in k

m / h over this stretch.
Physics
1 answer:
Leno4ka [110]3 years ago
5 0

Answer:

v?

Explanation:

v = ∆s / ∆t

v =?

∆s = 236 - 218 = 18km

=t = 10: 30 - 10:15 = 15 minutes to hour 15/60 = 0.25h

v = 18 / 0.25

v = 72km / h

speed of 72km / h

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What leads astronomers to believe that some large moons associated with the giant planets have compositions that are roughly hal
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3 years ago
A 6.60-kg block slides with an initial speed of 1.56 m/s up a ramp inclined at an angle of 28.4° with the horizontal. The coeffi
Vlad [161]

Answer:

The distance travel by block before coming to rest is 0.122 m

Explanation:

Given:

Mass of block m = 6.60 kg

Initial speed of block v _{i} = 1.56 \frac{m}{s}

Final speed of block v_{f} = 0 \frac{m}{s}

Coefficient of kinetic friction \mu _{k} = 0.62

Ramp inclined at angle \theta = 28.4°

Using conservation of energy,

Work done by frictional force is equal to change in energy,

  \mu _{k} mgd \cos 28.4 =  \Delta K - \Delta U

Where \Delta U = mg d\sin 28.4

\mu _{k} mgd \cos 28.4 =  \frac{1}{2}mv_{i} ^{2} - mgd\sin 28.4

\mu _{k} mgd \cos 28.4 +mgd\sin 28.4  =  \frac{1}{2}mv_{i} ^{2}

d(6.60 \times 9.8 \times 0.62 \times 0.879 + 6.60 \times 9.8 \times 0.475) = \frac{1}{2} \times 6.60 \times (1.56)^{2}

 d = 0.122 m

Therefore, the distance travel by block before coming to rest is 0.122 m

7 0
3 years ago
4 identical coins of mass M and radius R are placed in a square, so the center of each coin lies on a corner of the square. The
kati45 [8]

Answer:

I_{total} = 10 M R²

Explanation:

The concept of moment of inertia in rotational motion is equivalent to the concept of inertial mass for linear motion. The moment of inertia is defined

     I = ∫ r² dm

For body with high symmetry it is tabulated, in these we can simulate them by a solid disk, with moment of inertia for an axis that stops at its center

       I = ½ M R²

As you hear they ask for the moment of energy with respect to an axis parallel to the axis of the disk, we can use the theorem of parallel axes

        I = I_{cm} + M D²

Where I_{cm} is the moment of inertia of the disk, M is the total mass of the system and D is the distance from the center of mass to the new axis

Let's apply these considerations to our problem

The moment of inertia of the four discs is

    I_{cm} = I

    I_{cm} = ½ M R²

     

For distance D, let's use the Pythagorean Theorem. As they indicate that the coins are touched the length of the square is L = 2R, the distance from any spine to the center of the block is

         D² = (R² + R²)

         D² = R² 2

Let's calculate the moment of inertia of a disk with respect to the axis that passes through the center of the square

     I = ½ M R2 + M R² 2

     I = 5/2 M R²

This is the moment of inertia of a disc as we have four discs and the moment of inertia is a scalar is additive, so

   I_{total} = 4 I

   I_{total} = 4 5/2 M R²

    I_{total} = 10 M R²

5 0
3 years ago
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4.
Irina18 [472]

Answer: harder

Explanation: nothing is impossible, therefore is harder because the absence of light will not ¨reflect¨the colors to the retina of the eyes

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3 years ago
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