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azamat
2 years ago
13

A juggler has three objects in the air simultaneously. The masses of the objects are m, 2m, and 3m. At a particular instant, the

ir respective vertical velocities are v, 0, and -v, where positive velocity is upward.1) What is the magnitude of the acceleration of the centre of mass of the three-object system at this instant?a) zerob) g/3c) g/2d) ge) g/6
Physics
1 answer:
Vladimir [108]2 years ago
7 0

Answer:

the result  a_{cm} = g   .The correct answer is d

Explanation:

For this problem let's start by finding the center of mass of objects

         x_{cm} = 1 / M ∑ x_{i}  m_{i}

we apply this equation to our case

        M = m + 2m + 3m

       M = 6m

        x_{cm} = 1 / 6m (x₁ m + x₂ 2m + x₃ 3m)

        x_{cm} = 1/6 (x₁ + 2 x₂ + 3x₃)

We apply Newton's second law to this center of mass

         dp / dt = M a

         d (M v_{cm}) / dt = M a

let's find the speed of the center of mass

        v_{cm} = 1 / 6m (m v + 2m 0 - 3m v)

        v_{cm} = ⅓ v

         M d v_{cm}/ dt = M a

         d v_{cm} / dt = a

at the center of mass the external force of the system is applied, which is the force of gravity

         dv_{cm} / dt = g

therefore the result

               a = g

 

The correct answer is d

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A 37 N block rests on a horizontal surface. The coefficients of static and kinetic friction between the surface and the block ar
Ne4ueva [31]

Answer:

The frictional force acting on the block is 14.8 N.

Explanation:

Given that,

Weight of block = 37 N

Coefficients of static = 0.8

Kinetic friction = 0.4

Tension = 24 N

We need to calculate the maximum friction force

Using formula of friction force

f=\mu mg

Put the value into the formula

f=0.8\times37

f=29.6\ N

So, the tension must exceeds 29.6 N for the block to move

We need to calculate the frictional force acting on the block

Using formula of frictional force

f = \mu N

Put the value in to the formula

f=0.4\times37

f=14.8\ N

Hence, The frictional force acting on the block is 14.8 N.

6 0
3 years ago
Fill out the blanks, this is for science!
dusya [7]
Faster and higher I believe.
8 0
3 years ago
Read 2 more answers
A box with mass (m) it's sliding along on a friction-free surface at 9.87 m/s at a height of 1.81 meters. It travels down the hi
Rus_ich [418]
A) The answer is 11.53 m/s

The final kinetic energy (KEf) is the sum of initial kinetic energy (KEi) and initial potential energy (PEi).
KEf = KEi + PEi

Kinetic energy depends on mass (m) and velocity (v)
KEf = 1/2 m * vf²
KEi = 1/2 m * vi²

Potential energy depends on mass (m), acceleration (a), and height (h):
PEi = m * a * h

So:
KEf = KEi + <span>PEi
</span>1/2 m * vf² =  1/2 m * vi² + m * a * h
..
Divide all sides by m:
1/2 vf² =  1/2 vi² + a * h

We know:
vi = 9.87 m/s
a = 9.8 m/s²
h = 1.81 m

1/2 vf² =  1/2 * 9.87² + 9.8 * 1.81
1/2 vf² = 48.71 + 17.74
1/2 vf² = 66.45
vf² = 66.45 * 2
vf² = 132.9
vf = √132.9
vf = 11.53 m/s


b) The answer is 6.78 m

The kinetic energy at the bottom (KE) is equal to the potential energy at the highest point (PE)
KE = PE

Kinetic energy depends on mass (m) and velocity (v)
KE = 1/2 m * v²

Potential energy depends on mass (m), acceleration (a), and height (h):
PE = m * a * h

KE = PE
1/2 m * v² = m * a * h

Divide both sides by m:
1/2 * v² = a * h
v = 11.53 m/s
a = 9.8 m/s² 
h = ?

1/2 * 11.53² = 9.8 * h
1/2 * 132.94 = 9.8 * h
66.47 = 9.8 * h
h = 66.47 / 9.8
h = 6.78 m
3 0
3 years ago
A chemist needs to order an element that will not react with any other element. Which element should he order
Gwar [14]

Answer:

Helium

Explanation:

Helium is the least reactive element, since it is a noble gas with the smallest amount of valence rings.

4 0
3 years ago
When the palmaris longus muscle in the forearm is flexed, the wrist moves back and forth. If the muscle generates a force of 49.
UkoKoshka [18]

Answer:

1.1397 Nm

Explanation:

When the palmaris longus muscle in the forearm is flexed, the wrist moves back and forth.

If the muscle generates a force

F =  49.5 N and r = 2.65 cm , then the torque is equal to rF

we see that r = 2.65 cm = 0.0265 m

therefore

torque = 0.0265 x 49.5

= 1.1397 Nm

4 0
2 years ago
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