Hey there! Welcome to our cool blog post with multiple-choice questions (MCQs) on “Work and Energy” for Class 9 Physics. It’s a perfect spot to quiz yourself and discover some awesome science facts!
“Work and Energy” helps us understand how things move and what makes them go faster, slower, or stop. Work is all about the effort needed to move something, and energy is what we need to do the work. It’s like when you push a skateboard: the push is the work, and the food you ate that gave you the strength to push is the energy.
So, let’s dive into these questions and explore the amazing world of work and energy together. It’s a fun way to learn and get smarter about how things work in the world around us. Ready for the challenge? Let’s get started!
1. Which of the following scalar quantity has the same unit as energy?
Answer:
Explanation:
Energy, work, and force all have the unit of joules (J) in the SI system. However, they represent different physical quantities.
2. The work done by a force acting on an object is zero if the force is:
Answer:
Explanation:
Work is calculated as the product of force and the displacement in the direction of the force. If the force is perpendicular to the direction of motion, the displacement in the direction of the force is zero, hence the work done is zero.
3. Potential energy is the energy possessed due to:
Answer:
Explanation:
Potential energy is the energy an object has due to its position relative to other objects or due to its configuration.
4. What is the work done on an object moving in a circular path?
Answer:
Explanation:
The force acting on an object moving in a circular path is perpendicular to the displacement at every point. Thus, the work done is zero.
5. In which of the following scenarios is no work done?
Answer:
Explanation:
Even though force is applied on the wall, there’s no displacement of the wall, thus the work done is zero.
6. The ability of a body to do work due to its motion is called:
Answer:
Explanation:
Kinetic energy is the energy a body has because of its motion.
7. The energy stored in a stretched rubber band is:
Answer:
Explanation:
The stretched rubber band has energy due to its changed configuration, which is a form of potential energy.
8. A body at rest can have:
Answer:
Explanation:
A body at rest can have energy due to its position or configuration, which is potential energy.
9. Work is said to be done when:
Answer:
Explanation:
Work is done when there is a force causing a displacement in the direction of that force.
10. A machine that is 100% efficient:
Answer:
Explanation:
A 100% efficient machine would convert all input energy into useful work and would waste no energy.
11. Conservation of energy principle states that:
Answer:
Explanation:
The principle of conservation of energy states that the total energy in an isolated system remains constant, though it can change forms.
12. When an apple falls from a tree, the kinetic energy of the apple increases because:
Answer:
Explanation:
As the apple falls, it gains speed and its potential energy due to height decreases, converting into kinetic energy.
13. Work done by the gravitational force on a satellite moving around the Earth is:
Answer:
Explanation:
The gravitational force acts towards the center of the Earth, and the displacement of the satellite is perpendicular to this force. Therefore, the work done is zero.
14. Which energy form is primarily used by plants for photosynthesis?
Answer:
Explanation:
Plants capture solar energy using chlorophyll in their cells and convert it into chemical energy through the process of photosynthesis.
15. If the speed of an object is halved, its kinetic energy will be:
Answer:
Explanation:
Kinetic energy is given by the formula KE = 1/2 * m * v^2. If the speed (v) is halved, then the kinetic energy becomes proportional to the square of half the speed, which is one-fourth of the original energy.