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2 years ago

16. Olympic ice skaters are able to spin at about 5 rev/s.

Physics

1 answer:

Wittaler [7]2 years ago

5 0

Answer:

a) w = 31.4 rad / s, b) a = 118.4 m / s²

Explanation:

a) let's reduce to the SI system

w = 5 rev / s (2pi rad / 1 rev)

w = 31.4 rad / s

b) the expression for the centripetal acceleration is

a = v² / r

linear and angular variables are related

v = w r

we substitute

a = w² r

a = 31.4² 0.120

a = 118.4 m / s²

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Answer:

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Explanation:

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3 years ago

Find the unknown mass of the block 1 needed to balance the bar. Assume that the mass of the bar is negligible. Block 1 is locate

Natasha2012 [34]

Answer:

Incomplete question: The masses of the blocks m₂ = 1.5 kg and m₃ = 2 kg

Explanation:

Given data:

L₁ = length = 0.85 m

L₂ = 0.25 m

L₃ = 0.5 m

m₂ = 1.5 kg

m₃ = 2 kg

Question: Find the unknown mass of the block 1 needed to balance the bar, m₁ = ?

The torque is zero (intermediate point of the bar)

$-m_{1} gL_{1} +m_{2} gL_{2} +m_{3} gL_{3} =0$

Is negative because mass 1 is to the left of the coordinate system (see the diagram)

$m_{1} =\frac{m_{2} gL_{2}+m_{3} gL_{3} }{L_{1} } =\frac{(1.5*0.25)+(2*0.5)}{0.85} =1.6176kg$

4 0

3 years ago

A hunter points a rifle directly at a coconut that he intends to shoot off a tree. It so happens that the coconut falls from the

yan [13]

Answer:

It hits the coconut

Explanation:

The coconut fell immediately after the trigger was pulled as a result of the impact made by the bullet on the coconut. The Third Law of motion states that : For every action, there is an equal and opposite reaction. The action was performed when the bullet struck the coconut, while the coconut reacted by falling of the tree.

4 0

3 years ago

a system of four particles moves along one dimension. the center of mass of the system is at rest, and the particles do not inte

Zinaida [17]

The velocity of the particle 4 at time, t = 2.83 s, is -14.1 m/s.

The given parameters;

m1 = 1.45 kg, v1(t) = (6.09m/s) + (0.299m/s^2) × t

m2 = 2.81 kg, v2(t) = (7.83m/s) + (0.357m/s^2) × t

m3 = 3.89 kg, v3(t) = (8.09m/s) + (0.405m/s^2) × t

m4 = 5.03kg

The velocity of the center mass of the particles is calculated as;

McmVcm = m1v1 + m2v2 +m3v3+m4v4

Vcm= m1v1 + m2v2 +m3v3 +m4v4/ Mcm

0 = m1v1 + m2v2 +m3v3 +m4v4/ Mcm

m1v1 + m2v2 +m3v3+m4v4 = 0

m4v4 = -(m1v1 + m2v2 +m3v3)

v4 =-(m1v1 + m2v2 +m3v3)/ m4

The velocity of particle 1 at time, t = 2.83 s;

vi = 6.09 + 0.299× 2.83

v1 = 6.94 m/s

The velocity of particle 3 at time, t = 2.83 s;

v2 = 7.83 + 0.357 × 2.83

v2 = 8.84 m/s

The velocity of particle 3 at time, t = 2.83 s;

v3 = 8.09 + 0.405 × 2.83

v3 = 9.24 m/s

The velocity of particle 3 at time, t = 2.83 s;

v4 = - (m1v1 + m2v2 + m3v3)/m4

v4 = -(1.45×6.94 + 2.81×8.84 + 3.89×9.24)/5.03

v4 = -14.4 m/s

Thus, the velocity of the particle 4 at time, t = 2.83 s, is -14.1 m/s.

Learn more about Velocity here:

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5 0

1 year ago

Two identical blocks, block A and block B, are placed on different horizontal surfaces. Block A is initially at rest on a smooth

Nostrana [21]

Answer:

(D) Va > Vb. The forces between the atoms in a block and the atoms in a surface oppose the motion of the block and are greater on average for block B.

Explanation:

Given that, Two identical blocks, block A and block B, are placed on different horizontal surfaces. Block A is initially at rest on a smooth surface, while block B is initially at rest on a rough surface.

And now, a constant force F₀ is exerted on each block for a time Δt.

Now, speeds of blocks A and B are vA and vB respectively.

In case of block A the surface is smooth, so there is no opposing force.

Whereas as, in case of block B, the surface is rough which means friction opposes the motion

So, some of the applied force is used to overcome this friction which makes the speed of block B vB to be less than that of block A vA.

⇒ Va > Vb.

And completely eliminating friction is not possible.

so, even smooth surface has friction which is very very little.

so, The forces between the atoms in a block and the atoms in a surface oppose the motion of the block and are greater on average for block B.

3 0

3 years ago