Tag: physics

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Multiple choice physics heat - measurement introduction to temperature application of various thermometric scales different types of thermometers

A piece of lead falls from height of $100m$ on a fixed non-conducting slab which brings it to rest. if the specific heat of lead is $30.6 cal/kg ^ \circ C $ the increase in temperature of the slab immediately after collision is  

  1. ${6.72^ \circ }C$
  2. ${7.62^ \circ }C$
  3. ${5.62^ \circ }C$
  4. ${8.72^ \circ }C$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Potential energy lost (mgh) is converted into heat (ms deltaT). Using g = 9.8 m/s^2, mgh = m * 30.6 * 4.184 * deltaT (converting cal to Joules). The mass cancels out, leading to deltaT = (9.8 * 100) / (30.6 * 4.184) approx 7.65 C.

Multiple choice physics heat - measurement introduction to temperature application of various thermometric scales different types of thermometers

A physicist says "a body contains $10\ joule$ heat" but a physics learner says "this statement is correct only when the body is in liquid state". Mark correct option or options :

  1. physicist statement is correct

  2. physics learner's statement is correct

  3. both statements are correct

  4. both statements are wrong
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Heat is a form of energy in transit between systems due to a temperature difference; it is not a state function or a property contained within a body. Therefore, saying a body 'contains' heat is physically incorrect regardless of its state.

Multiple choice physics heat - measurement introduction to temperature application of various thermometric scales different types of thermometers

Two identical rods of a mental are welded in series then 20 cal of heat flows through them in  4 minute. If the rods are welded in parallel then same amount of heat will flow in 

  1. 1 minute

  2. 2 minute

  3. 4 minute

  4. 15 minute
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$dq/dt = [(AK)/2x][T2-T1] = 20/4 = 5.$

 $Therefore ( AK/x)(T2-T1) = 10$

When they are one above the other,

$dq/dt = 2Ak/x][T2-T1] =20/t$

Therefore$t = 2\times10  = 20/t$

Therefore$ t = 1 min$

Multiple choice physics heat - measurement introduction to temperature application of various thermometric scales different types of thermometers

A liter of air at $20^oC$ is heated until both the pressure and the volume are tripled, what is the tempertare then.

  1. $2637^oK$
  2. $927^oK$
  3. $200^oK$
  4. $977^oK$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Applying the formula

$PV=nRT$
$\dfrac { { P } _{ 1 } }{ { V } _{ 1 } } =\dfrac { { P } _{ 2 } }{ { V } _{ 2 } } =\dfrac { { T } _{ 1 } }{ { T } _{ 2 } } $    [$R$ is constant]
Let ${ P } _{ 1 }=P$  and ${ V } _{ 1 }=V$
As given ${ P } _{ 2 }=3P$   ${ V } _{ 2 }=3V$
${ T } _{ 1 }={ 20 }^{ 0 }C=20+2+3=293$
${ T } _{ 2 }=?$
$\dfrac { PV }{ 3P\times 3V } =\dfrac { 293 }{ { T } _{ 2 } } $
$\dfrac { 1 }{ 9 } =\dfrac { 293 }{ { T } _{ 2 } } $
${ T } _{ 2 }=293\times 9=2637$
$\therefore$    New temperature $=2637$.

Multiple choice physics gravitation tides movements of ocean and sea water circulation of ocean water

What are known as Spring Tides?

  1. When sun and moon are aligned causes strong high and low tides

  2. When sun and moon are not aligned causes strong high and low tides

  3. When sun and moon are aligned causes only low tides

  4. When sun and moon are not aligned causes only high tides
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Tide with the greatest difference between the high and low tide, 

that occurs just after a new or full moon is a spring tide.

Multiple choice physics gravitation tides movements of ocean and sea water circulation of ocean water

A stone drop from height 'h' reaches at earth surface in 1 sec. If the some stone taken to moon and drop freely from height h then it will reaches at the surface of moon in the time:

  1. $\sqrt { 6 } sec$

  2. 9 sec
  3. $\sqrt { 3 } sec$

  4. 6 sec
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using h = 0.5 * g * t^2, we have h = 0.5 * g_earth * (1)^2, so h = 0.5 * g_earth. On the moon, g_moon = g_earth / 6. Thus, h = 0.5 * (g_earth / 6) * t_moon^2. Substituting h, we get 0.5 * g_earth = 0.5 * (g_earth / 6) * t_moon^2, so t_moon^2 = 6, t_moon = sqrt(6).