Tag: physics

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Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

A lead ball moving with velocity v strikes a wall and stops. I 50% of its energy is converted into heat, then what will b the increase in temperature? (Specific heat of lead is s)

  1. $\dfrac { 2{ v }^{ 2 } }{ Js } $

  2. $\dfrac { { v }^{ 2 } }{ 4Js } $

  3. $\dfrac { { v }^{ 2 }s }{ J } $

  4. $\dfrac { { v }^{ 2 }s }{ 2J } $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

0.5 * (0.5 * m * v^2) = m * s * delta T * J. 0.25 * m * v^2 = m * s * delta T * J. delta T = v^2 / (4 * J * s).

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

In an energy recycling process, $x _ { g }$ of steam at $100 ^ { \circ } C$ becomes water at $100 ^ { \circ } \mathrm { C }$ which converts $\mathrm { Yg }$ of ice at $0 ^ { \circ } \mathrm { C }$ into water at $100 ^ { \circ } \mathrm { C }$ . The ratio XY will be

  1. $\dfrac { 1 } { 3 }$

  2. $\dfrac { 2 } { 3 }$

  3. $3$

  4. $2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heat released by steam condensing: x * L_v = x * 540 cal. Heat absorbed by ice melting and warming: Y * L_f + Y * 1 * 100 = Y * 80 + Y * 100 = 180Y. Equating: 540x = 180Y. x/Y = 180/540 = 1/3.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

The work done on the particle of mass m by a force $ \overrightarrow { F } =K\left[ \frac { X }{ \left( X^ 2+y^ 2 \right)^{1/2}  } \hat { i } +\frac { y }{ \left( X^ 2+y^ 2 \right)^{1/2}   } \hat { j }  \right]  $ (k being a constant of appropriate simensions), when the particle is taken from the point (a,0) to the point (0,a) along a circular path of radius a about the origin in the X-y plane 

  1. $ \frac {2k\pi}{a} $

  2. $ \frac {k\pi}{a} $

  3. $ \frac {k\pi}{2a} $

  4. 0
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

Which of the following energy conversions take place in a torch?

  1. electrical $\rightarrow$ chemical $\rightarrow$ light

  2. chemical $\rightarrow$ electrical $\rightarrow$ light

  3. electrical $\rightarrow$ light $\rightarrow$ chemical

  4. light $\rightarrow$ chemical $\rightarrow$ electrical
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The chemicalenergy stored in batteries gets transformed into electrical energy through the wires. This then gets transformed into light energy that you see.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

An electric heater is used by us to convert electrical energy to:

  1. heat energy

  2. light energy

  3. both a and b

  4. chemical energy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An electric heater is used to obtain heat energy. For light energy a bulb or other light sources are used.
An electric heater is used to convert electrical energy to heat energy.