Test: Force and Energy - Class 6 MCQ

The amount of work done is directly related to the force applied to an object and the distance over which the force is applied. Mathematically, work (W) is calculated as the product of force (F) and displacement (d) in the direction of the force (W = F * d). Understanding the dependence of work on applied force is fundamental to grasping the principles of mechanical work in physics.

Energy is defined as the ability to do work. It exists in various forms, such as kinetic energy (related to motion) and potential energy (related to position). The concept of energy is central to understanding the capacity of a system to perform work or undergo changes. Recognizing the role of energy in different processes is crucial in analyzing physical phenomena.

The correct answer is Kinetic.

• Kinetic energy: The kinetic energy of an object is the energy that it possesses due to its motion.
• The formula of kinetic energy KE = 1/2 mv²
• Kinetic energy is an example of the scalar quantity which means that the quantity has only magnitude and no direction.
• The unit of the kinetic energy is Joule. (J = kg m²/s²)
• An object of mass "m" places at a height "h" possess potential energy which is equal to "mgh", where g = 10 m/s² which is the acceleration due to gravity.

Burning fuels releases heat energy. This process involves the chemical reaction of combustion, where the stored energy in the fuel is converted into thermal energy. The heat generated is often harnessed for various applications, such as heating homes, powering engines, or generating electricity. Recognizing the source of heat energy from fuel combustion is important in understanding energy transformations.

• Statement-1: "When one body moves or tries to move on the surface of another body, its speed continuously decreases."

  • This is true. The frictional force opposes the motion of one object sliding over another, causing a reduction in the speed of the moving object. Friction tends to slow down the object, which is why objects eventually come to a stop unless an external force is applied.

• Statement-2: "Friction is a contact force."

  • This is also true. Friction is a contact force because it arises from the interaction between the surfaces of two objects that are in physical contact with each other. It does not act at a distance but requires the presence of surfaces in contact.

Thus, both statements are correct, making the correct answer Option C (Both statements are correct).

Work is done when a force acts on an object and causes it to move through some distance. In the context of physics, work is defined as the product of force and displacement. It is a scalar quantity and is measured in joules (J). Work can be positive, negative, or zero, depending on the angle between the force and the direction of motion. Understanding the concept of work is essential in analyzing various physical phenomena, from simple mechanical tasks to complex energy transformations.

Pressure is defined as the ratio of force to the area over which it is applied. Mathematically, it is given by:

Pressure = Force/Area

• Surface is related to the area but not the precise term for the physical quantity of interest.
• Volume and distance are not related to pressure in this context.

Thus, the correct answer is Option D (area).

To find the force applied, we can use Newton's Second Law of Motion, which states:

F = m × a

Where:

• F is the force
• mmm is the mass (2 kg)
• aaa is the acceleration (2 m/s²)

Now, substituting the given values:

F = 2 kg × 2 m/s² = 4 N

So, the force applied is 4 N.

Answer: A (4N).

The minimum force required to overcome the interlocking between two stationary surfaces and set an object in motion is known as static friction. It is the frictional force that resists the initial movement of an object.

• Rolling friction occurs when an object rolls over a surface.
• Sliding friction occurs when an object slides over a surface.
• Kinetic friction is the friction acting on an object that is already in motion.

Thus, the correct answer is Option A (Static friction).

The treaded soles of shoes are designed to increase the grip and provide better traction, especially on slippery or uneven surfaces. The grooves and patterns in the sole help to channel water or debris away and enhance friction, making it less likely to slip.

• Option B (Increase the life of the shoe) is not directly related to the tread; the purpose of the tread is primarily to enhance grip.
• Option C (Decrease the rate of friction) is incorrect because the tread increases friction to improve grip.
• Option D (Reduce the amount of material) is not the primary purpose of treaded soles.

Therefore, the correct answer is Option A (Increase the grip of the shoe).