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Initial velocity, u = ? 

Final velocity, v = 0 m/s 

Retardation, 

a = -2.5 m/s² 

Time, t = 10s 

v = u + at 

u = 25 m/s

Uniform linear motion is uniform motion along a linear path or a straight line. T he direction of motion is fixed. So, it is not accelerated. For e.g.: a car running with uniform speed of 10km/hr on a straight road. 

Uniform circular motion is uniform motion along a circular path. T he direction of motion changes continuously. So, it is accelerated. For e.g.: motion of earth around the sun.

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.

1. Select two positions (say A and B) 50 meters apart in the ground. 

2. Ask some students to stand at point A. 

3. Ask another group of students with stop watches to stand at B.

4. When you clap your hand, the students at A start running towards the point B in any direction or path. 

5. At the same time the students at B start their stop watches. 

6. Observe that for each runner there is a student at B to measure the time taken for completing the race. 

7. Note the time taken by each student to cover the distance between the points A and B in the table given below.

8. The student who took the least time to reach B (from A) is said to be the fastest runner. 

9. The student who is fastest runner has the greatest average speed. 

10. Thus we measure the average speed of any moving body.

• Carefully whirl a small object on the end of the string in the horizontal plane.
• Release the object while it is whirling on the string. 
• We observe that the body along the tangent at the point where we released the body. 
• Try to release the object at different points on the circle and observe the direction of motion of object after it has been released form the string. 
• We will notice that the object moves on a straight line along the tangent to the circle at the point where we released it.

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

(D) velocity, displacement and force

Speed not a vector

(C) Magnitude and direction both

Correct option is D) 2 ms^-1

Any object which is in motion possesses acceleration.

The correct answer is b) uniform acceleration

(D) Linear motion 

True 

\(velocity=\frac{Displacement}{Time}\) 

Now, equal displacement in equal interval of time means \(\frac{Displacement}{Time}\) = Constant 

Thus, Velocity = Constant and hence the motion is uniform motion.

A ball falls down vertically. Its motion is  

2. linear 

If a body covers equal distance in equal interval of time, the motion is said to be

1. uniform

Correct option is A) same

C) Acceleration

Time is an example of Scalar

Correct option is A) scalar

a) Speed

b) Acceleration

Correct option is B) 2g

C) instantaneous speed

False 

A quantity which can be represented completely by magnitude alone is not a vector quantity, but a scalar quantity. A scalar quantity has only magnitude. 

Example can be distance, speed, etc.

False 

In one dimensional motion average velocity and instantaneous velocity are not always unequal. 

They are equal when motion of the body is a uniform motion that is if the velocity remains constant.

False 

Velocity and Speed are not measured in different units. They both have same unit that is ms^-1 . 

\(velocity=\frac{Displacement(m)}{Time(s)}\)

\(speed =\frac{Distance(m)}{Time(s)}\)

 Thus, from above we can clearly infer that both velocity and speed have same units of measurement.

Correct option is A) Speed

Negative acceleration is also known as retardation.

Dynamics is the branch of physics and a sub branch of Mechanics. Dynamics is concerned with the motion of material objects and also concerns with the cause of motion. It deals with the factors that affect motion such as force, mass, momentum and energy. 

Whereas, Statics deals with objects at rest and Kinematics deals with objects in motion without considering the cause of motion.

The acceleration of a body is zero that has a uniform velocity.

The average velocity of a moving body can be zero.

Negative acceleration is nothing but retardation. 

Acceleration is rate of change of velocity. 

But negative acceleration means that the rate of change of velocity is negative or velocity decreases. 

Example: 

(1) When we apply brakes in a moving car, then negative acceleration acts on it and the car stops. 

(2) When we throw a ball upwards, then also negative acceleration acts on it. Thus, when the ball reaches the highest point, velocity of the ball becomes zero.

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.

i) The palk taken by a ball which was released from the top of the inclined plane. Here the direction of motion remains constant but velocity gradually increases. 

ii) Whirl a stone which is tied to the end of the string continuously. Here it’s direction of motion changes but speed remains constant.

 iii) The path taken by a stone, which was thrown into the air. Here speed and direction of the motion both changes simultaneously.

When a car moves from parking area to the mall and back from mall to the parking area, the average speed is certain but the average velocity is zero.