PHYSICS XI Ch#3 Quiz 2

Rocket works on the principle of Newton 3rd law of moption and Law of conservation of momentum.

Newton 3rd law of motio; Gases are burned out and exert action force downward and then dus to reaction force rocket moves upward.

Law of conservation of momentum; By conserving its linear momentum rocket moves faster as going upward.

In projectile motion no force is acting along horizontal direction, therefore its horizontal velocity remains same.

As horizontal velocity remains same so horizontal acceleration becomes zero whisch also remains constant(same).

Vertical accelration during projectile motion is equal to gravitational acceleration which also remains same.

Only vertical component of velocity varies from point to point during projectile motion.

In projectile motion no force is acting along horizontal direction, therefore its horizontal velocity remains unchanged.

Reason;

For angles of projection, which exceed or fall short of 45° by equal amounts, the ranges are equal.

For long range the path of projectile is elliptical.

For short range the path of projectile is parabolic.

Displacement can be defined as

"how much you are far from starting point"

then "if the starting and ending point of a body is same then its displacement can be zero'

And for a body in motion it must have some velocity and it must cover some distance, therefore velocity and distance covered cannot be zero for a body in motion.

As retarted motion means speed is decreasing and the acceleration is negative, therefore The slope of velocity-time graph for retarded motion is negative.

Negative acceleration is also called as retardation.

Anti parallel (opposite) velocities are added.

Therefore if bodies are moving in opposite direction with velocity V, then relative velocity between them is equal to 2V.

The area between the velocity-time graph and the time axis is numerically equal  to the distance covered by the object.

Using S=vt.