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Vanyuwa [196]
2 years ago
14

A boy is pulling his two sisters on a sled.

Physics
1 answer:
OlgaM077 [116]2 years ago
4 0

Answer:

Explanation:

The oly way we can figure this out is if the boy is pulling the sled at a constant velocity. If not, we need a value for acceleration, and you don't have that here. If the boy is pulling the sled at a constant velocity, then the value for acceleration is 0, making this a really simple problem. I'm going with that, since there is no way to answer you otherwise. If velocity is not constant, please either repost the question or put it in the notes section under the question as it stands. If acceleration is 0, then

F - f = ma becomes

F - f = m(0) which is

F - f = 0 and

F = f which says that the applied force is the same as the frictional force. We need then to find the frictional force, which has an equation of

f = μF_n where normal force is the same as the weight of the 2 girls. We will find that, then:

Each girl's mass is different so the normal force/weight equation is

w = (30.0)(9.8) + (40.0)(9.8) to get

w = 290 + 390 and

w = 680. Plug that into the frictional force equation:

f = (.120)(680) so

f = 82N

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A small balloon is released at a point 150 feet away from an observer, who is on level ground. If the balloon goes straight up a
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Answer:

\dfrac{dz}{dt}=0.65\ ft/s

Explanation:

Given that

x= 150 ft

\dfrac{dy}{dt}= 7\ ft/s

y= 14 ft

From the diagram

z^2=x^2+y^2

When ,x= 150 ft and y= 14 ft

z^2=150^2+14^2

z=\sqrt{150^2+15^2}

z=150.74 ft

z^2=x^2+y^2

By differentiating with respect to time t

2z\dfrac{dz}{dt}= 2x\dfrac{dx}{dt}+2y\dfrac{dy}{dt}

z\dfrac{dz}{dt}= x\dfrac{dx}{dt}+y\dfrac{dy}{dt}

Here x is constant that is why

\dfrac{dx}{dt}=0

z\dfrac{dz}{dt}= y\dfrac{dy}{dt}

Now by putting the values in the above equation we get

150.74\times \dfrac{dz}{dt}=14\times 7

\dfrac{dz}{dt}=\dfrac{14\times 7}{150.74}\ ft/s

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A constant power is supplied to a rotating disc .the relationship of angular velocity of disc and number of rotations made by th
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Answer: Just before its hits the ground it becomes kinetic energy and when it hits the ground it becomes in another form of energy (acoustic energy or thermal energy, for example)

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In this sense, according to the Conservation of Energy principle: <em>"energy is not created or destroyed, it is transformed."</em>

So, in the case of the apple, its total energy is conserved.

When the apple is hanging from a limb, it has zero kinetic energy K_{o}=0 (because it is at rest) and has gravitational potential energy U_{o}, which depends on the mass m, the acceleration due gravity g and the height h:

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When the apple falls, just before its hits the ground, this gravitational potential energy transforms in kinetic energy K_{1} (since the apple is moving), which depends on the mass and velocity V of the apple:

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When the apple hits the ground, the gravitational potential energy is zero (h=0) and the kinetic energy transforms into some other form of energy (acoustic energy or thermal energy, for example).

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