Tag: air resistance

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Questions Related to air resistance

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

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?

  1. $1.33 m$
  2. $2 m$
  3. $10 m$
  4. $1 m$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using the center of mass principle, the initial center of mass of the system (men + boat) is at a certain position. When they move to the center, the boat must shift to keep the center of mass stationary because there are no external horizontal forces.

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

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

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

State whether the given statement is true or false:

Fluid friction is more than solid friction.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Static friction is the force that is the greatest. This is because it opposes motion the strongest between the various types of friction. Friction is greatest in the absent of lubrication,and since there is presence of fluid lubricant in fluid friction it has less friction as compared to solid friction,and in solid friction there is no presence of any lubricant.Hence the given statement is false.

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

A man of mass $m$ walks from end $A$ to the other end $B$ of a boat of mass $M$ and length $l$. The coefficient of friction between the man and the boat is $ \mu $ and neglect any resistive force between the boat and the water.

  1. If the man runs at his maximum acceleration, the acceleration of the boat is $ (m/M)g $.
  2. The maximum time take by the men to reach the other end of the boat is $ \sqrt { \dfrac { 2Ml }{ (M+m)\mu g } } $.
  3. If the man runs at his maximum acceleration, the acceleration of the boat is $ \dfrac { m }{ m+M } \mu g $.
  4. The minimum time take by the men to reach the other end of the boat is $ \sqrt { \dfrac { 2ml }{ (M+m)\mu g } } $.
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

The motion of the man and the boat involves Newton's laws and friction. The acceleration of the boat is derived from the force balance, and the time taken is derived from the kinematic equations under constant acceleration.