# Motion in One Dimension Physics

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Motion in One Dimension Physics : : Equations of Motion Under Gravity

Mechanics can be divided into 2 Parts :

(A) Statics :

• Which deals with the study of stationary objects.

(B) Dynamics :

• Which deals with the study of moving objects.

Terms Regarding Motion

Displacement :

• The change in position of the body in a certain direction is known as displacement. It is a vector quantity.

Distance :

• The total path transversed by the body between initial and final states is called distance. It is a scalar quantity.
• Displacement may be positive, negative or zero but distance is always positive.

Velocity : • Time rate of change of displacement is called velocity.
 Velocity ( v ) = Displacement ( x ) / Time ( t )
• It is a vector quantity and may be positive or negative.
 Average Velocity = Total Displacement / Total Time
• Average velocity is zero, if the body returns to starting point in the given time interval.
• If the body covers first half distance with velocity V1 and next half with velocity V2, then
 Average Velocity = 2 V1*V2 / V1+V2
• If a body travels with uniform velocity V1 for time t1 and with uniform velocity V2 for time t2, then
 Average Velocity = V1t1 + V2t2 / t1+t2

Speed :

• It is a scalar form of velocity and is defined as the distance traveled in 1s.
• If the body covers a distance d in time t, then
 v = d / t ( or ) Average Speed = Total Distance / Total Time
• If the body covers first half distance with speed u and next half with speed v, then
 Average Speed = 2uv / u+v

Acceleration :

• Time rate of change of velocity is known as acceleration.
• It is a vector quantity. If Δ v is the change in velocity in time Δt, then
 α = Δ v / Δ t
• Negative acceleration is known as retardation. It indicates that the velocity of the object is decreasing with respect to time.
• Acceleration is uniform when neither its direction nor magnitude changes with respect to time. #### JEE Main

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