Tag: physics

Questions Related to physics

The deeper we go inside a flowing river, fluid friction:

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. decreases

  2. increases

  3. remains same

  4. becomes zero

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Correct Option: B
Explanation:

Fluid friction increases with the depth of a flowing liquid.

Which of the following statements indicates advantage of fluid friction?

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. Walking on road

  2. Rolling stone on carpet

  3. Lubricating machine parts

  4. None of the above

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Correct Option: C
Explanation:

Lubricating machine parts indicates advantage of fluid friction. This helps in lowering the friction and thus helps to keep parts of machinery in good condition for some time. 

Fill in the blank. 
Water offers _______ fluid friction as compared to honey. 
physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. higher

  2. lower

  3. same

  4. zero

Show answer
Correct Option: B
Explanation:

Water, having less density than honey, offers lower fluid friction as compared to honey.

Hailstones falling from atmosphere relates to:

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. static friction

  2. rolling friction

  3. sliding friction

  4. fluid friction

Show answer
Correct Option: D
Explanation:

Hailstones falling from atmosphere is related to Fluid friction. Fluid friction occurs when there is resistance between particles in fluids or in gases.

Aeroplanes are streamlined to reduce friction.

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. True

  2. False

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Correct Option: A
Explanation:

Fluid

Aeroplanes are streamlined to reduce:

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. fluid friction.

  2. sliding friction.

  3. kinetic friction.

  4. limiting friction.

Show answer
Correct Option: A
Explanation:

Fluid friction occurs when a solid object travels through a liquid or gas. Aeroplanes are streamlined to reduce the fluid friction.

A spherical body of radius R consists of a fluid of constant density and is in equilibrium under its own gravity. If$ P(r)$ is the pressure at $r(r < R)$, then the correct option(s) is(are)?

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. $P(r=0)=0$

  2. $\dfrac{P(r=3R/4)}{P(r=2R/3)}=\dfrac{63}{80}$

  3. $\dfrac{P(r=3R/5)}{P(r=2R/5)}=\dfrac{16}{21}$

  4. $\dfrac{P(r=R/2)}{P(r=R/3)}=\dfrac{20}{27}$

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Correct Option: B

Mr. Verma (50 kg) and Mr. mathur (60 kg) are sitting at the two extreames of 4 m long boat (40 kg) standing still in water. to discuss a mechanics problem, they come the middle of the boat . neglecting friction with water, how far does the boat move in the water during the process?

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. $1.33 m$

  2. $2 m$

  3. $10 m$

  4. $1 m$

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Correct Option: A

Smooth surface produces ----- friction than a rough surface.

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. Less

  2. More

  3. Constant

  4. None of these above

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Correct Option: A
Explanation:

[A]  less

As the coefficient of friction $( \mu)$ is less for smooth surfaces 
so they produce less friction than rough surface.

The arrow with a pointed tip can move faster in air than that of with a blunt tip.

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

Show answer
Correct Option: A
Explanation:

A pointed tip is more sharper than a blunt tip. So the air resistance for the pointed tip is less than that of the blunt tip. Since the air resistance opposes the motion, so the pointed can tip move faster than that of blunt tip. Thus, the given statement is true.