Tag: forces - vectors and moments

Quizzes (8) Questions (83)

Questions Related to forces - vectors and moments

Multiple choice physics forces - vectors and moments the turning of couple couple rotational motion of a rigid body and moment of inertia turning effect of force

State whether true or false.
A couple can never be replaced by a single force.

  1. True

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

A couple is defined as a pair of two equal and opposite parallel forces acting along two different lines. A couple can produce roatation in the body but not the translational motion. A single force can produce translation motion in the body. Thus the given statement is true that a couple can never be replaced by a single force.

Multiple choice physics forces - vectors and moments the turning of couple couple rotational motion of a rigid body and moment of inertia turning effect of force

State whether true or false.
Only a couple can produce pure rotation in a body.

  1. True

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

A couple is defined as a pair of two equal and opposite parallel forces acting along two different lines. Since net force acting on the body is zero, so the body is in translatory equilibrium. A couple produces torque which rotates the body. Thus the given statement is true that only a couple can produce pure rotation in a body.

Multiple choice physics forces - vectors and moments the turning of couple couple rotational motion of a rigid body and moment of inertia turning effect of force

While opening a tap with two fingers, the forces applied by the fingers are:

  1. equal in magnitude

  2. parallel to each other

  3. opposite in direction

  4. all the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A couple has to be applied to the tap in order to open it. A couple is the combination of two equal and opposite parallel forces acting at different axes. Thus option D is correct.

Multiple choice physics forces - vectors and moments the turning of couple couple rotational motion of a rigid body and moment of inertia turning effect of force

$ML^2T^{-2}$ is the dimensional formula for

  1. moment of inertia

  2. pressure

  3. elasticity

  4. couple acting on a body
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\left[ MOI \right] =\left[ M{ R }^{ 2 } \right] =\left[ { M }^{ 1 }{ L }^{ 2 }{ T }^{ 0 } \right] \ \left[ Pressure \right] =\left[ N/{ M }^{ 2 } \right] =\left[ { M }^{ 1 }{ L }^{ -1 }{ T }^{ -2 } \right] \ \left[ Couple \right] =\left[ N.{ M } \right] =\left[ { M }^{ 1 }{ L }^{ 2 }{ T }^{ -2 } \right] $

Multiple choice physics forces - vectors and moments the turning of couple couple rotational motion of a rigid body and moment of inertia turning effect of force

An automobile engine develops $100$ $kW$ when rotating at a speed of $1800\ rev/min$. The torque it delivers is

  1. $3.33\ N-m$

  2. $200\ N-m$

  3. $530.5\ N-m$

  4. $2487\ N-m$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$Power\quad P=100kW\quad =100000W\ w=1800\times \cfrac { 2\pi  }{ 60 } \quad rad/s\ \quad =60\pi \quad rad/s\ P=torque\times w\ torque=530.5\quad Nm$

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

State whether given statement is True or False.

Centre of gravity of a freely suspended body always lies vertically below the point of suspension.

  1. True

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

Yes, Centre of gravity of a freely suspended body always lies vertically below the point of suspension. The center of gravity of an object is the point you can suspend the object from without there being any rotation because of the force of gravity, no matter how the object is oriented. If you suspend an object from any point, let it go and allow it to come to rest, the center of gravity will lie along a vertical line that passes through the point of suspension. Unless you've been exceedingly careful in balancing the object, the center of gravity will generally lie below the suspension point.

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

Where is the centre of gravity of a uniform ring situated ?

  1. At the centre of ring.

  2. At the centre of semicircular ring

  3. At the centre of radius

  4. cant say
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Centre of gravity means a point from which the weight of a body or system may be considered to act. In uniform gravity it is the same as the centre of mass.For regular bodies centre of gravity lies at the centre of the body.Hence we know that there will be a centre for a uniform ring lamina.Hence this centre of the ring will be centre of gravity.

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

Stability and center of gravity of an object whose stability can be increased by

  1. lowering center of gravity and increasing area of base

  2. lowering center of gravity and decreasing area of base

  3. moving center of gravity higher and increasing areas of base

  4. moving center of gravity higher and decreasing area of base
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The position of the centre of gravity of an object affects its stability. The lower the centre of gravity is, the more stable the object. The higher it is the more likely the object is to topple over if it is pushed.
In general, increasing the size of the base (that is area) of support increases stability.