Science Question Answer (2 Marks)

A freely falling body has non-uniform motion because it covers smaller distances in the initial '1 second' intervals and larger distances in the later '1 second' intervals, i.e., it covers unequal distances in equal intervals of time.

We have to plot a graph between velocity and time. From the graph we can conclude that the curve is a straight line showing uniform acceleration.

An important characteristic of uniform circular motion is that the direction of motion in it changes continuously with time, so it is accelerated.
Centripetal force brings about uniform circular motion.

If an object changes the location relative to the time other than the other, then this state of the object is called motion/ motion. In general terms the meaning of speed - the change in the position of the object is called speed.

When a body covers equal distances in equal intervals of time in a particular direction however small or big the time interval may be, the object is said to have uniform velocity.

Speed of a body is the distance travelled by it per unit time. The S.I. unit of speed is m/s.

1. Graph (c) represents a cricket ball thrown vertically upwards and returning to the hands of the thrower.
2. Graph (a) represents a trolley decelerating to a constant speed and then accelerating uniformly.

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Uniform linear motion is uniform motion along a linear path or a straight line. The direction of motion is fixed. So, it is not accelerated.
For example: A car running with uniform speed of 10km/hr on a straight road.
Uniform circular motion is uniform motion along a circular path. The direction of motion changes continuously. So, it is accelerated.
For example: Motion of earth around the sun.

1. The train has a uniform velocity.
2. There is no acceleration.

v = u + at is the first equation of motion. It gives the velocity acquired by a body in time t when the body has initial velocity u and uniform acceleration a.

When a body moves in a circular path with uniform speed (constant speed), its motion is called uniform circular motion.
For example:

1. Artificial satellites move in uniform circular motion around the earth.
2. Motion of a cyclist on a circular track.

1. Average Speed: The average speed of a body is the total distance travelled divided by the total time taken to cover this distance.
2. Uniform Speed: A body has a uniform speed if it travels equal distances in equal intervals of time, no matter how small these intervals may be.

The motion of a body which is moving with constant speed in a circular path is said to be accelerated because its velocity changes continuously due to the continuous change in the direction of motion.

The motion of a body which is moving with constant speed in a circular path is said to be accelerated because its velocity changes continuously due to the continuous change in the direction of motion.

Yes, uniform circular motion is accelerated because the velocity changes due to continuous change in the direction of motion.

	Distance	Displacement
1.	distance has only magnitude, with no specified direction.	Diplacement has magnitude as well as direction.
2.	It is a scalar quantity.	It is vector quantity.
3.	Two different distance can be added directly.	We have to follow the vector addition method to add displacements.

One difference in digramatic form is as follows:

Here the curved line is the distance traveled and the straight line is the magnitude of the displacement.

1. Distance travelled = 6km.
2. Displacement = zero (since final position is same as initial position).

Motion of a boy from his home to shop (in one direction) and back to home (in its reverse direction) is an example of a situation in which a body has a certain average speed but its average velocity is zero.

1. The body has uniform velocity if its displacement-time graph is a straight line. If the straight line is parallel to the time axis then the magnitude of uniform velocity is zero.
2. The body has a uniform acceleration if its velocity-time graph is a straight line. If the straight line is parallel to the time axis then the magnitude of uniform acceleration is zero.