Chapter 2 Work and Energy
- What is the law of conservation of energy? Energy can neither be created nor destroyed. It can be converted from one form into another. Thus, the total amount of energy in the univers... 1
- Into which form are the chemical energy stored in the exploding firecrackers converted to? Energy is transformed from one form to another. In the example stated, the exploding firecrackers convert the chemical energy stored in them... 1
- Ajay and Atul have been asked to determine the potential energy of a ball of mass m kept on a table as shown As seen from the picture, the heights of the ball with respect to Ajay and Atul are different. Also, given that the potential energy is rela... 1
- What is the potential energy? Potential energy of the object is the energy stored in it because of its specific state or position. 1
- What is kinetic energy? Kinetic energy is the energy that an object has because of its motion. The kinetic energy gained by the object is the work done by a force t... 1
- Define energy. What is its unit? Energy is the capacity of a body to perform work. Unit of energy is the same as that of work. In the SI system, the unit is joule, while in... 1
- Pravin has applied a force of 100 N on an object, at an angle of 600 to the horizontal. The object gets displaced Given here is θ=60⁰ and F=100N, while W= 400J , SO s=? Take the equation W = F s Cos θ Replace with values 400= 100 × s × ½ Hence, 400 / 100... 1
- Calculate the work done to take an object of mass 20 kg to a height of 10 m. (g = 9 8 m/s2) Suppose mass of the object (m) = 20 kg, while height (s) = 10 m given that g = 9.8 m/s² The value for F = mg = 20 × (-9 8) (Because the disp... 2
- Write about the National Physical Laboratory. The National Physical Laboratory, conceptualized in 1943 was situated in New Delhi and functions under the Council of Scientific and Industr... 1
- Give an example of where the work done by the gravitational force is zero. Take the example of an artificial satellite moving around the earth in a circular orbit. The work done by the gravitational force is zero as... 1
- With the force and the displacement specified, define the work done by the force. Work done by the force in the various scenarios are explained here: 1. The work done by the force is positive when the force and the displac... 2
- Define the relationship between joule and erg using the equation. It is given that 1 newton (1N) = 10⁵ dyne, while 1m = 10² cm. So, if Work= forces × displacement, then 1 joule = 1 newton × 1 m 1 joule = 10... 1
- Explain unit of work as per SI and CGS system. Given that, Work = Force × Displacement, the unit of force in SI system is newton (N), while the unit of displacement is metre (m). Hence, t... 1
- The work done on an object does not depend on .... (i) displacement (ii) applied force The work done on an object does not depend on initial velocity of the object. 1
- If we increase the velocity of a car moving on a flat surface to four times its original speed, its potential energy If we increase the velocity of a car moving on a flat surface to four times its original speed, its potential energy will not change. 1
- The total energy of an object falling freely towards the ground ... (i) decreases (ii) remains unchanged The total energy of an object falling freely towards the ground remains unchanged. 1
- The potential energy of your body is least when you are ..... (i) sitting on a chair (ii) sitting on the ground The potential energy of your body is least when you are sleeping on the ground. 1
- While dragging or lifting an object, negative work is done by (i) the applied force (ii) gravitational force While dragging or lifting an object, the negative work is done by frictional and gravitational force, respectively. 1
- Power is a measure of the ....... (i) the rapidity with which work is done (ii) amount of energy required to perform Power is a measure of the rapidity with which work is done 2
- Which of the forces involved in dragging a heavy object on a smooth, horizontal surface, have the same magnitude? The gravitational force and the reaction force in vertical direction have same magnitude. Friction is not action as the horizontal surface i... 1
- Joule is the unit of ... (i) force (ii) work (iii) power (iv) energy Joule is the unit of work and energy 2
- For work to be performed, energy must be .... (i) transferred from one place to another (ii) concentrated correct option is a For work to be performed, energy must be transferred from one place to another. 1
- Why is the work done on an object moving with uniform circular motion zero? Answer: Because the centripetal force is always perpendicular to the direction of motion, so W = Fscos 90^° = 0 . In uniform circular motion... 1
- If an object has 0 momentum, does it have kinetic energy? Explain your answer. Answer: No. If an object has zero momentum, its kinetic energy is also zero. Momentum is p = mv . The mass m of an object is never zero, so... 1