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2 years ago

A sled of mass 8 kg slides along the ice. It has an initial speed of 4 m/s but

Physics

1 answer:

marysya [2.9K]2 years ago

6 0

As our story begins, the sled ... whose mass is 8 kg ... is sliding along the ice at a speed of 4 m/s.

The sled's kinetic energy is (1/2 m v²) = (4 kg · 16 m²/s²) = 64 J .

After what seems like only the blink of an eye, the sled is no longer sliding. It is stationary. Motionless. At Rest. Just sitting there !

Its speed has been reduced to zero and ... because kinetic energy is the energy of motion ... the sled's kinetic energy is now also zero. Sixty-four Joules of energy have disappeared !

How can this be ? ! ? We know that energy is conserved. It can never just appear out of nothing, and it can never just disappear into nothing. If energy suddenly appears, it had to come from somewhere, and if energy suddenly disappears, it had to go somewhere. So where did our 64 Joules of kinetic energy go ?

It went into the ice, THAT's where ! We can say that the sled did 64J of work, and melted a thin slick layer of water on the surface of the ice. OR we can say that friction did NEGATIVE 64J of work on the sled, to cancel the 64J that it had originally, sap its kinetic energy, and bring it to rest.

I think choice-B was supposed to say "B. -64J", but somebody typed it sloppily and neglected to proofread it before posting.

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3 years ago

A space vehicle approaches a space station in orbit. The intent of the engineers is to have the vehicle slowly approach, reducin

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2 years ago

The bob (weight) at the end of a pendulum has a mass of 0.3 kilograms. The bob is pulled to position B and allowed to swing. It

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0.147 J

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The total energy that has been transformed into thermal energy is equal to the loss of gravitational potential energy between the initial situation (bob at h=0.5 m above the ground) and the final situation (bob back but at h=0.45 m above the ground).

Therefore, we have

$E_{thermal}=\Delta U=mgh_1 - mgh_2 = mg(h_1 -h_2)$

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3 years ago

What are the four main reasons as to why, despite having an abundance of minerals and natural resources, Pakistan has been unabl

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Answer:

GDP growth rate is low

Political instability

Lack of technical skills due to low literacy rate

Pressure from neighboring countries

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Gross Domestic Product growth rate of Pakistan is much lower than many developed countries. The GDP growth rate for Pakistan is nearly 5% which is not even stable and it variate from plans. Due to which Pakistan is unable to use its available resources to the fullest. Also one of major issue is political instability in the country. After the loss of great leader Quaid e Azam Pakistan has not faced any loyal leader till date.

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