Olympiad Test : Force, Work And Energy - 1 - Class 5 MCQ

Change in the state of rest of uniform motion is brought about by:
There are several factors that can bring about a change in the state of rest or uniform motion. Let's explore each option and determine which one is the correct answer.
A: Energy
- Energy is a fundamental concept in physics, but it does not directly cause a change in the state of rest or uniform motion. Energy can be converted from one form to another, but it does not initiate motion or change in motion by itself.
B: Force
- Force is the correct answer. According to Newton's first law of motion, an object at rest will remain at rest, and an object in motion will continue in motion with a constant velocity unless acted upon by an external force. In other words, a force is required to change the state of rest or uniform motion of an object.
C: Acceleration
- Acceleration is related to the change in velocity of an object, not the change in the state of rest or uniform motion. Acceleration occurs when there is a change in speed, direction, or both.
D: None of the above
- This option is incorrect as the correct answer is force.
In conclusion, the correct answer is Force. A change in the state of rest or uniform motion is brought about by the application of an external force on an object.

Friction force always opposes the state of motion.
Explanation:
Friction is a force that opposes the relative motion between two surfaces that are in contact with each other. It acts in the opposite direction to the applied force or motion. Here's a detailed explanation of why friction force opposes the state of motion:
1. Nature of friction: Friction is a contact force that arises due to the irregularities present on the surfaces of objects. These irregularities interlock when two surfaces come in contact, leading to resistance against motion.
2. Types of friction: There are mainly two types of friction - static friction and kinetic friction. Static friction acts on objects at rest, while kinetic friction acts on objects in motion.
3. Static friction: When an object is at rest, the applied force must overcome the static friction to set the object in motion. The static friction force increases as the applied force increases until the point of maximum static friction is reached. This maximum static friction force is equal to the applied force, preventing motion.
4. Kinetic friction: Once an object is in motion, the friction force acting on it is called kinetic friction. Kinetic friction is generally less than the maximum static friction and opposes the direction of motion. It acts to slow down or stop the object.
5. Energy dissipation: Friction converts kinetic energy into other forms of energy, such as heat, sound, or wear and tear. This conversion of energy is one of the reasons why friction always opposes motion.
In conclusion, friction force always opposes the state of motion by resisting the relative motion between two surfaces. It is an essential force that affects everyday activities like walking, driving, and many other interactions between objects.

Why do we sprinkle powder before playing carom?
There are several reasons why we sprinkle powder before playing carom. Let's explore them in detail:
1. To decrease friction:
- The primary reason for sprinkling powder on the carom board is to reduce friction between the striker and the board.
- Friction can prevent smooth movement of the striker, affecting the accuracy and speed of the shots.
- By reducing friction, the striker can slide more easily across the board, allowing for better control and accuracy during gameplay.
2. To increase smoothness:
- Sprinkling powder on the carom board also helps to increase the smoothness of the playing surface.
- The powder fills in any imperfections or rough spots on the board, creating a more even and consistent surface.
- This smoothness ensures that the striker glides effortlessly across the board, making gameplay more enjoyable and precise.
3. To improve shot techniques:
- The reduced friction and increased smoothness provided by the powder allow players to execute various shot techniques more effectively.
- Shots like the "finger flick" or "follow shot" require a smooth and slippery surface to achieve the desired outcome.
- The powder helps players to execute these shots with greater ease and control.
4. Depending on the type of game:
- In certain variations of carom games, such as "doubles," where four players are involved, the powder may be used differently.
- In some cases, the powder may be used to increase friction to improve the grip of the striker for specific shots.
- Alternatively, it may be used to decrease friction for smoother shots in other game variations.
5. None of the above:
- While the options provided in the question are all valid reasons for using powder in carom, it is important to note that there may be other reasons specific to individual preferences or regional traditions.
In conclusion, the primary reason for sprinkling powder before playing carom is to decrease friction and increase the smoothness of the playing surface. This allows for better control, accuracy, and execution of various shot techniques during gameplay.

Explanation:
When the load is nearer the fulcrum than the effort, it is easier to move. This can be understood using the principles of lever mechanics.
Lever Mechanics:
- A lever is a simple machine that consists of a rigid bar (lever) that rotates around a fixed point called the fulcrum.
- The effort is the force applied to move the lever, and the load is the resistance to be moved.
- The distance between the fulcrum and the effort is called the effort arm, and the distance between the fulcrum and the load is called the load arm.
Working of a Lever:
- In a lever, the effort and the load are balanced by the principle of moments. The moment of a force is the product of the force and the perpendicular distance from the fulcrum.
- When the load is nearer the fulcrum than the effort, it means the load arm is smaller than the effort arm.
- The effort required to move an object is inversely proportional to the length of the effort arm.
- Therefore, when the load is nearer the fulcrum than the effort, the effort arm is longer, and less effort is required to move the load.
Conclusion:
- When the load is nearer the fulcrum than the effort, it is easier to move because the effort arm is longer, reducing the amount of force required to overcome the resistance.

- When the load is further from the fulcrum than the effort, it becomes more difficult to move.
- The lever arm of the load is longer, requiring more force to lift or move the load.
- Thus, it requires more effort to achieve the desired movement, making option D correct.

Forces acting on the rock:
- Gravity, acting downward: Gravity is a force that pulls objects towards the center of the Earth. It acts vertically downward on the rock, causing it to accelerate downwards.
- The normal force, acting upward: The normal force is the force exerted by a surface to support the weight of an object resting on it. In this case, the ground exerts an upward normal force on the rock to counteract the downward force of gravity.
- Friction, acting opposite the direction of motion: Friction is a force that opposes the motion of objects in contact with each other. As the rock slides across the ground, there will be a frictional force acting in the opposite direction of its motion. This force helps to slow down the rock's motion.
- All of the above: In this scenario, all three forces (gravity, normal force, and friction) are acting on the rock, making option D, "All of the above," the correct answer.
Summary:
When you kick a rock and it starts sliding across the ground, gravity pulls it downward, the ground exerts an upward normal force, and friction acts to oppose its motion. These forces collectively determine the rock's motion and behavior.

Problem:
Two rubber bands stretched the standard distance cause an object to accelerate at 2 m/s². Suppose another object with twice the mass is pulled by four rubber bands stretched the standard length. The acceleration of this second object is:
A: 16 m/s²
B: 8 m/s²
C: 4 m/s²
D: 2 m/s²

To solve this problem, we can use Newton's second law of motion, which states that the force acting on an object is equal to the mass of the object multiplied by its acceleration.
Let's denote the mass of the first object as m1 and the mass of the second object as m2. The force acting on the first object is given by F1 = m1 * a1, where a1 is the acceleration of the first object (2 m/s²).
Now, let's consider the second object. Since it has twice the mass of the first object, its mass is 2m1. The force acting on the second object is given by F2 = (2m1) * a2, where a2 is the acceleration of the second object.
We know that the force exerted by the rubber bands is directly proportional to the number of rubber bands used. Since the second object is pulled by four rubber bands instead of two, the force acting on it is four times greater than the force acting on the first object. This can be expressed as F2 = 4 * F1.
Setting F1 = F2, we have:
m1 * a1 = (2m1) * a2
a1 = 2a2
Given that a1 = 2 m/s², we can solve for a2:
2 = 2a2
a2 = 1 m/s²
Since the acceleration of the second object is 1 m/s², which is half of the acceleration of the first object, the correct answer is C: 4 m/s².

To do work on an object, you need both force and energy:

- Force: It's necessary to apply a force to move or change the state of an object. Without force, no work is done according to physics.
- Energy: It is the capacity to do work. Energy is required to apply force over a distance.

Without energy, a force cannot be applied, and without force, energy cannot cause motion. Therefore, both are essential for work.

A simple machine:

There are a few characteristics that define a simple machine:

1. Is used to make work easier:
- A simple machine is designed to reduce the amount of force or effort required to perform a specific task.
- It allows us to accomplish work with less effort or in a more efficient manner.
- By changing the direction or magnitude of a force, simple machines can make tasks easier to perform.

2. Does not necessarily have an engine:
- Unlike complex machines that often rely on engines or motors, simple machines do not require external power sources to operate.
- Simple machines use basic principles of physics to multiply or redirect forces, making them easier to handle.

3. Is simple because it is easy to use:
- Simple machines are designed with simplicity in mind, making them easy to understand and operate.
- They often have uncomplicated mechanisms and are user-friendly, making them accessible to a wide range of individuals.

4. Is not actually simple to use:
- While simple machines are designed to be user-friendly, this does not mean that using them is always easy or straightforward.
- Understanding the proper application and use of a simple machine may require some knowledge and practice.

Therefore, the correct answer is A. Is used to make work easier. Simple machines are designed to reduce the effort required to perform a task, making work easier and more efficient.

Introduction:
To press or fasten objects like the book binding press, an example of a specific type of mechanism is required. In this case, the answer is the screw.
Explanation:
The book binding press is used to apply pressure and fasten objects together. This process is achieved through the use of a screw mechanism. Here's how it works:
1. Screw: A screw is a simple machine that consists of a threaded cylindrical rod called the screw and a matching threaded hole called the nut. The screw and nut have helical threads that allow them to rotate and move relative to each other.
2. Threaded Rod: The threaded rod of the screw is turned using a handle or a wrench. As it rotates, the screw moves linearly along its axis, either towards or away from the nut.
3. Nut: The nut is fixed in position, and as the screw moves, it presses against the objects that need to be fastened together.
4. Pressure and Fastening: As the screw moves further into the nut, the distance between the objects decreases, creating pressure. This pressure holds the objects tightly together, providing a secure binding.
5. Book Binding Press: In the case of a book binding press, the screw mechanism is used to apply pressure evenly across the bookbinding, ensuring that the pages are tightly bound together.
Therefore, the correct answer is C: Screw.