Definitions [12]
Define 1 Dyne.
1 dyne is that force which when acting on a body of mass 1 gram, produces an acceleration of 1 cm s-2 in it.
1 dyne = 1 g × 1 cm s-2.
Define contact forces.
The forces which are applied on a body through a connector, are called contact forces. Forces like Frictional force, Mechanical force, etc., are the forces of contact.
Define an Inclined plane.
An inclined plane is usually a smooth, flat rigid surface inclined at an angle (θ) to the horizontal. It is used to raise heavy loads with a relatively small force. The longer the slope, the smaller is the effort needed.
Force is defined as the rate of change of linear momentum of a body with respect to time.
A force is seen to act through direct contact of the objects or via one more object. Such a force is called 'Contact force.'
A force is applied between two objects even if the two objects are not in contact; such a force is called a 'Non-contact force.'
Define the term “weight of a body”
The weight of the body is the force with which the earth attracts it towards the centre. It depends on acceleration due to gravity.
Answer the following.
Define weight.
The gravitational force acting on an object is called the weight of the object.
"The motion of an object that does not move in a straight line is called ‘non-linear motion’."
A train or a moving vehicle on a road may travel in a straight line or in the same direction. This motion of an object is called linear motion. An object in linear motion shows displacement along a straight line."
Define Speed.
The distance covered by a body in a unit time is called its speed. It is also defined as the rate of change position of a body in any direction.
Speed = distance/time
Define speed Mention its formula and unit.
Speed is the rate of change of distance.
Formula: Speed = distance /time
Unit is meter/second (m/s)
Formulae [1]
\[\overset{\rightarrow}{\operatorname*{F}}=\frac{d\overset{\rightarrow}{\operatorname*{p}}}{dt}=\frac{d(m\overset{\rightarrow}{\operatorname*{v}})}{dt}\]
or
\[\begin{array}
{rcl}\vec{F} & = & m\vec{a}
\end{array}\](if mass m is constant)
Key Points
- Force is a Vector Quantity
- Unit of Force is Newton (symbol N) or kilogram-force (symbol kgf), where 1 kgf = g N if g is the acceleration due to gravity at that place (= 9·8 m s-2 average value on the earth's surface).
