Test: Work, Force, Energy And Simple Machines - 2 - Class 5 MCQ

The lever is a simple machine with multiple uses:

• It helps to lift or move heavy weights easily.
• You can use it to open lids, like those of tins.
• It is also useful for cutting things efficiently.

A pulley is a simple machine that helps lift or move loads. It consists of two main parts:

• A grooved wheel that a rope or cable runs over.
• The rope or cable used to lift the load.

By pulling on one end of the rope, you can easily lift heavy objects with reduced effort.

The force the Earth always exerts on us is gravitational. This force pulls objects towards the center of the Earth.

• It keeps us grounded on the surface.
• It acts on all objects with mass.
• This force is also responsible for the weight we feel.

Muscular force is applied when we push or pull something using our muscles. A boy pushing a bicycle is an example of muscular force.

A fishing rod incorporates two simple machines:

• Wheel and axle: This is found in the reel, which helps in winding and unwinding the fishing line.
• Lever: The fishing rod itself acts as a lever, allowing for the casting and reeling in of fish.

These machines work together to enhance the efficiency and effectiveness of fishing.

The ability to perform work is primarily associated with energy. Here is a simplified explanation:

• Energy is the capacity to do work.
• It allows objects or systems to perform tasks.
• Without sufficient energy, work cannot be performed.

In physics, energy is a fundamental concept essential for understanding how work is done.

- When a ball is thrown upward, it moves against the force of gravity.
- Gravity is a natural force that pulls objects toward the center of the Earth.
- As the ball rises, it slows down until gravity overcomes its upward motion, causing it to fall back down.
- This is why the correct answer is B: Gravitational force.
- Without gravity, the ball would not come back down; it would continue to move indefinitely in the air.

Ensuring the moving parts of machines are well lubricated helps prevent accidents and ensures smooth operation. Additionally, sharp tools should be handled with care and stored properly.

The force between two surfaces in contact is called frictional force. This force:

• Acts to oppose the relative motion between the surfaces.
• Can be static, preventing motion, or kinetic, resisting motion.
• Depends on the nature of the surfaces and the force pressing them together.

A crane is a type of machine used to lift and move heavy loads. It operates using a system of pulleys and cables.

• Pulleys change the direction of the force applied, making it easier to lift heavy objects.
• Cranes use a combination of pulleys to multiply the lifting force.

This system allows for efficient lifting and movement of objects in construction and other industries.

The source of solar energy is the Sun.

• The Sun emits vast amounts of energy in the form of light and heat.
• This energy travels through space and reaches the Earth.
• Solar energy can be harnessed using technologies like solar panels.

A Solar Cooker is a device that uses the energy from the sun to cook food. It is an eco-friendly option that does not require fuel or electricity.

• Environmentally friendly: Uses renewable solar energy.
• Cost-effective: Reduces the need for conventional fuels.
• Simple to use: Often involves placing food in a container and allowing the sun to cook it.

Hydropower is a form of energy that is generated from the movement of water. It is considered a renewable energy source because water is continuously replenished by the water cycle.

• Water flows through turbines, converting kinetic energy into electricity.
• Hydropower plants can provide a stable and reliable power supply.
• It helps to reduce reliance on fossil fuels, contributing to lower carbon emissions.

This type of energy is widely used around the world and has been a key component of sustainable energy strategies.

The sun is not a direct source of electrical energy, though it is a source of solar energy. Electrical appliances like fans, washing machines, and computers use electrical energy generated at power stations and supplied to our homes through wires.

Explanation:
The surface of the ramp is made smoother because, there would be less friction opposing the box. Here's a detailed explanation:
Friction:
Friction is a force that opposes the motion of objects in contact with each other. When a box is being loaded onto a truck ramp, friction between the box and the ramp surface can make it difficult to push or slide the box. This friction force acts in the opposite direction of the applied force, making it harder to move the box.
Smooth Surface:
By making the surface of the ramp smoother, the amount of friction between the box and the ramp is reduced. A smooth surface allows the box to slide more easily, requiring less force to move it. This is because a smooth surface reduces the amount of roughness or irregularities that can cause the box to stick or catch on the ramp.
Less Friction:
With less friction opposing the box, it becomes easier to push or slide the box onto the truck ramp. This is beneficial when loading multiple boxes onto the truck, as it reduces the effort required and increases efficiency.
Conclusion:
So, the surface of the ramp is made smoother to reduce the friction opposing the box, making it easier to load the boxes onto the truck ramp.