Tag: turning on a pivot

Quizzes (4) Questions (28)

Questions Related to turning on a pivot

Multiple choice physics turning on a pivot the turning effect of a force moment of force or torque turning effect of force couple

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

  1. equal in magnitude

  2. parallel to each other

  3. opposite in direction

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

While opening a tap with two fingers, a couple should be applied which is defined as a pair of parallel equal forces acting in opposite direction about two different axis.

Multiple choice physics turning on a pivot the turning effect of a force moment of force or torque turning effect of force couple

On applying a constant torque on a body-

  1. linear velocity increases

  2. angular velocity changes

  3. it will rotate with constant angular velocity

  4. it will move with constant velocity
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A constant torque applied to a rigid body results in constant angular acceleration, which causes the angular velocity to change over time.

Multiple choice physics turning on a pivot the turning effect of a force moment of force or torque turning effect of force couple

It becomes easier to open or close a door turning about its hinges if the force is applied at the:

  1. Two third of the door

  2. Free edge of the door

  3. Middle of the door

  4. Point near the hinges
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Torque acting about any point O         $\tau _o = rF$                 for $sin\theta = 1$

where $r$ is the distance of the application of force from point O.
As  $r$ is maximum when a force is applied at the free end of the door, thus less amount of force is required to produce the same torque. Hence it is easier to open or close the door if force is applied at its free end. 

Multiple choice physics turning on a pivot the turning effect of a force moment of force or torque turning effect of force couple

State whether true or false.
A spanner with a longer handle can tighten nuts and bolts with less effort.

  1. True

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

We know, 

Moment of force = Force \times Distance between action point and force applied.
$\therefore T = F \times R$
As, R increases, T also increases.
So, we required to get less effort.

Multiple choice physics turning on a pivot the turning effect of a force moment of force or torque turning effect of force couple

For a rigit body, we know that if verious forces act at various points in it , the resultant motion is as if a net force acts on the CM(centre of mass)  causing translation and a net torque at the CM causing rotation around an axis through the CM. for the earth-sun system (approximating the earth as a uniform density sphere).

  1. the torque is zero

  2. the torque causes the earth to spin

  3. the rigid body result is not applicable since the earth is not ever approximately a rigid body

  4. the torque causes the earth to move around the sun
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the Earth-Sun system, the gravitational force acts on the Earth, and because the Earth is not a point mass but an extended body, the gravitational gradient creates a torque that contributes to the Earth's axial precession and spin dynamics.