Physics MCQs: Force

Study Notes

Moment of force is not measured in kg m.
A body is in equilibrium when the resultant of all forces acting on it is zero.
A couple is not an example of pushing a box.
Examples of dynamic equilibrium include a rain drop falling from a height and a stone tied to a string and whirled in a circular path.

Torque is the tendency of rotation of a body along any axis.
Torque depends on both force and moment arm.
If 150 N of force is applied on a spanner of 10 cm to open a nut, the length of the spanner when the force applied on it is 60 N is 25 cm.
Moment arm is the perpendicular distance from the axis of rotation to the point where the force is applied.

The centre of gravity of a hollow cone lies at a height of h/3 from the base.
For a stable equilibrium of a body, its centre of gravity must be above the base and near the centre of the body.
The position of the centre of gravity of a body depends on the distribution of mass.
The centre of gravity of a tennis ball is at its geometrical centre.
The point of intersection of diagonals is not the centre of gravity for a quadrilateral.
The centre of gravity for a ring is not within the material of the body.

In Uniform Circular Motion, the direction of motion is along the tangent to the circle.
Uniform Circular Motion is also called accelerated motion.
Clockwise moments are taken to be negative.
If the sum of clockwise moments acting on a body is equal to the sum of anticlockwise moments acting on it, then the body is balanced.
The net torque is zero when two children sitting on a see-saw are not swinging.