Science
- 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
- Determine the amount of work done when an object is displaced at an angle of 30o with respect to the direction of t Answer: W = Fscos 30^° = sqrt3/2Fs ≈ 0.866 Fs When a force F acts at an angle θ to the displacement s , only the component of the force alon... 1
- Prove that the kinetic energy of a freely falling object on reaching the ground is nothing but the transformation Answer: At height h the object has potential energy mgh and zero kinetic energy; on reaching the ground its kinetic energy is also mgh, so a... 1
- Derive the formula for the kinetic energy of an object of mass m, moving with velocity v. Kinetic energy is the energy possessed by an object by virtue of its motion. K.E=1/2 mV² Derivation: Let us consider an object of m which is... 1
- Explain the difference between potential energy and kinetic energy. Kinetic Energy Potential Energy (i) Kinetic energy is the energy possessed by the body due to its motion. (i) Potential energy is the energy... 1
- Does the angle of banking depend on the mass of the vehicle? It does not depends upon mass of the vehicle as it only depends upon:- 1.acceleration due to gravity 2.radius of curvature 3.speed of the ve... 1
- A person swims 100 m in the first 40 s, 80 m in the next 40 s and 45 m in the last 20 s. What is the average speed? formula for velocity is given as; v=x/t therefore, v₁=x₁/t₁=100m/40sec=2.5m/s. v₂=x₂/t₂=80m/40sec=2m/s v₃=x₃/t₃=45m/20sec=2.25m/s Vavg=V1+V2... 2
- A bullet having a mass of 10 g and moving with a speed of 1.5 m/s, penetrates a thick wooden plank of mass 90 g. Answer: 0.15 m/s Use the law of conservation of momentum: total momentum before = total momentum after. Convert masses to kg: bullet m₁ = 10... 1
- An object of mass 16 kg is moving with an acceleration of 3 m/s2 . Calculate the applied force. Answer: Force = 48 N; acceleration of the 24 kg object = 2 m/s² By Newton's second law, F = ma . For the 16 kg object: F = 16\ kg × 3\ m/s²... 1
- An object moves 18 m in the first 3 s, 22 m in the next 3 s and 14 m in the last 3 s. What is its average speed? Average speed = Total \ Distance/Total \ time = 18+22+14/3+3+3=54/9 =6m/s 1
- Take 5 examples from your surroundings and give explanation based on Newtons laws of motion. 1) When a ball is kicked in space, the ball keeps moving in one direction as there is no gravity. The ball stops when it hits an object or p... 2
- Give scientific reasons. d. The velocity of an object at rest is considered to be uniform. Velocity of an object is said to be uniform when its speed and direction does not change. The object at rest has uniform speed of zero all t... 1
- Give scientific reasons. c. It is easier to stop a tennis ball as compared to a cricket ball, when both are travelling Momentum of a body is the product of its mass and velocity i.e. p=mv and the rate of change of momentum of a body is equal to the force appl... 1
- Give scientific reasons. b. Even though the magnitudes of action force and reaction force are equal and their When two bodies interact, the action and reaction forces come into action. Even though their magnitude are same and their direction are oppo... 1