Uniform and Non-uniform motion

Uniform Motion

Definition

Uniform motion is a type of motion in which an object moves at a constant speed in a straight line. In other words, the object covers equal distances in equal intervals of time, without any changes in its direction or speed.

 It’s important to note that both conditions must be met:

1. The path must be straight
2. The speed must be constant for the motion to be considered uniform.

Another example of uniform motion is – Imagine you’re riding a bike on a straight path and you keep your speed steady, let’s say 10 miles per hour. You don’t speed up, slow down, or change your direction – you just keep going straight ahead at the same speed. That’s what we call uniform motion

Examples of uniform motion

1. A Car Traveling at a Steady Speed: If a car is traveling at a constant speed on a straight highway, say 60 miles per hour, then it is in uniform motion. Even though the car is moving, its velocity doesn’t change because its speed and direction remain constant.

2. A Clock’s Second Hand: The second hand on an analog clock moves in uniform motion. It completes a full circle (360 degrees) every 60 seconds, thus maintaining a constant speed and direction.

3. Earth’s Rotation: The Earth rotates on its axis in a consistent and steady manner. It completes one rotation every 24 hours, illustrating uniform motion. The speed and direction of Earth’s rotation do not change.

4. An Elevator Moving Up or Down: An elevator moving either up or down at a constant speed exemplifies uniform motion. If it’s moving at a steady rate of 1.5 meters per second, its speed doesn’t change unless it starts to slow down for stopping or speed up from a stop.

5. A Train Moving on a Straight Track: A train moving at a constant speed on a straight track is another example of uniform motion. The train maintains its speed unless the engineer applies the brakes or accelerates the engine. Even if the train is moving at a high speed, as long as the speed and direction are unchanging, it is demonstrating uniform motion.

Distance vs Time graph of uniform motion

 

Solved questions of uniform motion

Question 1.  A car moves at a constant speed of 60 km/hr for 5 hours. How far does it travel?

A) 300 km

B) 120 km

C) 60 km

D) 240 km

Solution: The distance traveled by an object moving at a constant speed is the product of the speed and time. Therefore, 60 km/hr * 5 hr = 300 km. So, the correct answer is A) 300 km.

Question 2. Which of the following is an example of uniform motion?

A) A roller coaster ride.

B) A car accelerating on a highway.

C) A clock’s second hand.

D) A basketball being dribbled.

Solution: Uniform motion refers to motion in a straight line at a constant speed. Therefore, the only correct option is C) A clock’s second hand.

Question 3. What does a straight line represent in a distance-time graph for an object in motion?

A) Non-uniform motion.

B) The object is at rest.

C) Uniform motion.

D) The object is accelerating.

Solution: A straight line in a distance-time graph indicates that the object is moving at a constant speed, covering equal distances in equal time intervals. So, the correct answer is C) Uniform motion.

Question 4. If a bicycle moves at a steady speed of 15 km/hr for 2 hours, then for how long should it travel at a speed of 20 km/hr to cover the same distance?

A) 1 hour

B) 1.5 hours

C) 2 hours

D) 3 hours

Solution: The distance covered at 15 km/hr for 2 hours is 30 km. To cover the same distance at 20 km/hr, the time taken would be Distance/Speed = 30 km / 20 km/hr = 1.5 hours. So, the correct answer is B) 1.5 hours.

Question 5. A train travels at a constant speed of 80 km/hr. How much distance will it cover in 45 minutes?

A) 30 km

B) 60 km

C) 40 km

D) 120 km

Solution: First, we convert the time from minutes to hours. 45 minutes = 45/60 = 0.75 hours. Then, we find the distance = Speed x Time = 80 km/hr x 0.75 hr = 60 km. So, the correct answer is B) 60 km.

Non – Uniform Motion

Definition

Non-uniform motion is a type of motion in which an object moves with a varying speed or changes its direction, or both. This means the object doesn’t cover equal distances in equal intervals of time. If the speed of the object changes while moving, or if the object changes its direction of motion, then the motion is called non-uniform. This also applies when an object follows a curved path, even if it’s moving at a constant speed, because the direction of motion is continually changing.

Examples of Non-uniform motion

1. A Car Stopping at a Red Light: If a car is driving down a city street, it will need to slow down and stop when it reaches a red light. When the light turns green, the car will accelerate back to its initial speed. The changing velocity (both speed and direction) indicates non-uniform motion.

2. A Roller Coaster Ride: Roller coasters are an excellent example of non-uniform motion. They continuously accelerate and decelerate, and change directions rapidly, creating a thrilling ride. This continuous change in speed and direction is what characterizes non-uniform motion.

3. A Baseball Being Hit: When a baseball player hits a ball, the ball initially accelerates rapidly as it leaves the bat, then it decelerates due to gravity and air resistance until it hits the ground, changing its speed and direction in the process. This is a clear instance of non-uniform motion.

4. A Bus on Its Route: A city bus often has to stop at various places to pick up and drop off passengers. Thus, it’s frequently slowing down, stopping, and then accelerating again, demonstrating non-uniform motion.

5. A Person Running in a Race: If a person is running in a race, they might start off at a slow pace to conserve energy, then gradually speed up as they approach the finish line, or slow down if they become tired. The speed of the runner changes based on their strategy and stamina, making this a non-uniform motion.

Distance vs Time graph of non-uniform motion

Solved questions of non-uniform motion

Question 1. Which of the following is an example of non-uniform motion?

A) A car moving at a constant speed on a straight highway.

B) A bike moving around a circular track at a steady speed.

C) The second hand of a clock.

D) A train moving at a constant speed on a straight track.

Solution: Non-uniform motion involves either a change in speed or direction, or both. Even if the bike is moving at a steady speed, its direction is constantly changing as it moves around the circular track. So, the correct answer is B) A bike moving around a circular track at a steady speed.

Question 2. What does a curved line represent in a distance-time graph for an object in motion?

A) The object is accelerating.

B) The object is at rest.

C) The object is moving at a constant speed.

D) The object is decelerating.

Solution: A curved line in a distance-time graph indicates that the object is either accelerating or decelerating, i.e., it’s moving at varying speeds. So, the correct answer is A) The object is accelerating.

Question 3.  An object moves from point A to B at a speed of 10 m/s, then it returns from B to A at a speed of 15 m/s. Is this motion uniform or non-uniform?

A) Uniform

B) Non-uniform

Solution: Even though the path is the same (from A to B and back), the object covers it at different speeds. Thus, the motion is non-uniform. The correct answer is B) Non-uniform.

Question 4. A car accelerates from 0 to 60 km/hr in 10 seconds. What type of motion is this?

A) Uniform motion.

B) Non-uniform motion.

Solution: Since the car is changing its speed (from 0 to 60 km/hr), this is an example of non-uniform motion. The correct answer is B) Non-uniform motion.

Question 5. A man jogs for 5 minutes, then sprints for the next 2 minutes, and finally walks for 8 minutes. What type of motion is this?

A) Uniform motion.

B) Non-uniform motion.

Solution: The man changes his speed at different intervals (jogging, sprinting, walking), hence this is an example of non-uniform motion. The correct answer is B) Non-uniform motion.

Difference between uniform and non-uniform motion 

Uniform Motion	Non-uniform Motion
The velocity (both speed and direction) remains constant over time.	The velocity changes over time. This means either the speed, the direction, or both changes.
Objects in uniform motion cover equal distances in equal intervals of time.	Objects in non-uniform motion do not cover equal distances in equal intervals of time.
The motion of a car moving at a constant speed on a straight road is an example of uniform motion.	The motion of a car accelerating or decelerating, or changing direction, is an example of non-uniform motion.
The path of the moving object can be a straight line or a circle (in cases where the speed is constant but the direction changes uniformly, as in the motion of a planet around the sun).	The path of the moving object can be irregular, and it can involve changes in speed, direction, or both.
Graphically, uniform motion can be represented by a straight line on a distance-time graph.	Non-uniform motion is represented by a curved line on a distance-time graph.
The rate of change of velocity is zero in uniform motion because the velocity remains constant.	The rate of change of velocity is not zero in non-uniform motion. This non-zero rate of change of velocity is also known as acceleration.

FAQ

Q1. What is uniform motion?

Uniform motion is a type of motion in which an object moves at a constant speed in a straight line. In other words, the object covers equal distances in equal intervals of time, without any changes in its direction or speed.

 It’s important to note that both conditions must be met:

 The path must be straight

 The speed must be constant for the motion to be considered uniform.

Q2. How can uniform motion be defined mathematically?

Uniform motion can be mathematically defined using the equation of motion, s = vt, where s is the distance traveled, v is the constant velocity, and t is time.

Q3. What is an example of uniform motion in real life?

A real-life example of uniform motion could be a train moving at a constant speed on a straight railway track.

Q4. How does uniform motion differ from non-uniform motion?

The difference lies in the speed. In uniform motion, speed remains constant over time, whereas in non-uniform motion, the speed of the object varies with time.

Q5. What role does uniform motion play in physics?

Understanding uniform motion is crucial in physics because it’s one of the simplest forms of motion to analyze and forms the basis of the laws of motion.

Q6. Can an object in uniform motion change its direction?

No, an object in uniform motion cannot change its direction. It moves in a straight line at a constant speed.

Q7. How can I calculate the speed of an object in uniform motion?

Speed can be calculated by dividing the total distance covered by the total time taken. For an object in uniform motion, this will be a constant value.

Q8. Does an object in uniform motion have acceleration?

No, an object in uniform motion does not have acceleration as its velocity (speed in a particular direction) remains constant.

Q9. How is uniform motion represented graphically?

Uniform motion is represented graphically as a straight line when we plot distance vs time.

Q10. What is the significance of the slope in a distance vs time graph of an object in uniform motion?

The slope of a distance versus time graph for an object in uniform motion represents the constant speed or velocity of the object