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# expression for kinetic energy class 9

The Questions and Answers of Mathematical expression of kinetic and potential energy are solved by group of students and teacher of Class 9, which is also the largest student community of Class 9. Time = 10 s m is the mass of the body. Where K.E. Write an expression for the kinetic energy of an object. The derivation of kinetic energy is given below so that students can understand the concept more effectively. Expression for K.E - KINETIC ENERGY-K.E = 1/2 mv2. derive equation for loss of kinetic energy in case of a completely inelastic collision in one dimension - Physics - TopperLearning.com | 98uzboee 1 unit of energy is equal to 1 kilowatt hour (kWh). Initially at point A, kinetic energy is zero and the body has only potential energy. Work is done whenever the given two conditions are satisfied: (i) A force acts on the body. Where, For example, a fast moving pebble can injure a person or break glass pane of window, energy of moving vehicle, a fast moving wind can damage many house, or wind can move blades of wind mill, etc. Answer : Books. at rest, u=0. Therefore we can say that kinetic energy is: Derivation of Kinetic Energy using Calculus. What is the kinetic energy of an object? (i) A force acts on the body. (i) A force acts on the body. As the object hits the hard ground, all its kinetic energy gets converted into heat energy and sound energy. Objects in motion possess energy, we call this energy kinetic energy. v 2 = 2as. Answer : Energy consumed by an electric heater can be obtained with the help ofthe expression, 1 kWh = 3.6 x 106 J Work done by gravity depends only on thevertical displacement of the body. Q 2 Page 152 - Write an expression for the kinetic energy of an object View Answer Q 3 Page 152 - The kinetic energy of an object of mass, m moving with a velocity of 5 m s–1 is 25 J. Answer : Q9 : The kinetic energy of an object of mass, m moving with a velocity of 5 m s-1  is 25 J. Does this violate the law of conservation of energy? Derive an expression for the kinetic energy of an object of mass m moving with a velocity V. (CBSE 2011, 2017) Answer: (a) Definition of energy : The capacity of doing work by a body or an object is known as the energy of the body or the object. Kinetic energy when the object was moving with a velocity 2 m s −1. Q6 : The potential energy of a freely falling object decreases progressively. This allows the train to move in the direction of force. Kinetic energy can be defined as the work needed to accelerate an object of a given mass from rest to its stated velocity. Kinetic energy - The energy possessed by virtue of its motion is said to be kinetic energy. Since, displacement is perpendicular to force, the work done is zero. Answer : (b) Define kinetic energy. Work done = Force x Displacement Hence, the energy consumed by the heater in 10 h is 15 kWh. The energy possessed by a body by virtue of its motion is called kinetic energy. What will be its kinetic energy when its velocity is doubled? Question 8. Kinetic energy provides a velocity to the bicycle. 15.6k SHARES. In fact, kinetic energy of an object moving with a certain velocity is equal to the work done to make it acquire that velocity. Why? Where, Kinetic energy, W= mgh 6)A moving bus,car,falling stone possesses kinetic energy. The kinetic energy of an object of mass, m moving with a velocity of 5 ms-1 is 25 J. 1 unit of energy is equal to 1 kilowatt hour (kWh). Therefore, there is a displacement in the train in the same direction. A body of mass 3.0kg and a body B of mass 10 kg are dropped simultaneously from a height of 9m. The derivation of kinetic energy is one of the most common questions asked in the examination. Work done by the force of gravity on an object depends only on vertical displacement. 7)A falling coconut, running athlete possesses kinetic energy. Q1 : Look at the activities listed below. Accordingly, the kinetic energy increases. Hence, kinetic energy = 25 x 4 = 100 J. Kinetic Energy Formula (Rotational) The rotational kinetic energy equation goes like this: K = (1/2) Iw 2 (It is the Rotational kinetic energy of an object with Moment of inertia I and angular velocity w) Types of Kinetic Energy. Answer : During the transformation, the total energy remains conserved. Answer : Answer : Obtain an expression for the kinetic energy of an object. as = 1/2 v 2. Hence, the work done is zero during the process of food grains getting dried in the Sun. This discussion on Mathematical expression of kinetic and potential energy is done on EduRev Study Group by Class 9 Students. To bring the object to rest, amount of work is required to be done on the object. If velocity is zero then K.E. Vertical displacement is given by the difference in the initial and final positions/heights of the object, which is zero. Starting with the work-energy theorem and Newton’s second law of motion we can say that. = 56 Nm A body can do different amount of work in different time intervals. Question 1. Answer : • A donkey is carrying a load on its back. So the kinetic energy at rest should be zero. SOLUTION: Kinetic energy of an object, where m = mass of the object and v = uniform velocity of the object. Has he done some work or not? During the process, total mechanical energy of the body remains conserved. The velocity of a body moving in a straight line is inereásed by applying constant force F, for some distance in the direction of motion. Q73: (a) Derive an expression to calculate the kinetic energy of a body. Write an expression for the kinetic energy of an object. W = mas ….. (1) By 3 rd eq n of motion, v 2 = u 2 + 2as. Work and Energy Class 9 MCQs Questions with Answers. Hence, the transformation of energy in the given situation can be shown as: Q4 : Certain force acting on a 20 kg mass changes its velocity from 5 m s -1to 2 m s -1. Answer: KE = $$\frac{1}{2}$$ mv 2. 2. Therefore, there is a displacement in the boat in the direction of force. Therefore, its kinetic energy becomes 4 times its original value, because it is proportional to the square of the velocity. Therefore, the work done by gravity on the given object is zero joule. Explain your answer. ∴W= mg x 0 = 0 Q11 : Define 1 watt of power: NCERT Solutions for Class 9 Science Chapter 11 PDF: Work and Energy chapter deals with concepts of conservation of energy, its types, and how work & energy are interrelated. Therefore, work done by force on the block will be positive. (ii) There is a displacement of the body by the application of force in or opposite to the direction of force. Hence, 20.8 x 104 J of work is required to stop the car. Kinetic energy when the object was moving with a velocity 2 m s −1. The kinetic energy of a body is the energy that it possessed due to its motion. What will be its kinetic energy when its velocity is doubled? Answer : Prove that the increase ¡n the kinetic energy of the body is equal to the work done by the force on the body. Now we already know that kinetic energy is the energy that it possessed due to its motion. Potential Energy Potential energy is the energy possessed by a body by virtue of its state of rest or deformed state i.e, the energy of an object due to its position or arrangement in a system is called potential energy. Write an expression for the kinetic energy of an object. Hence, work is done by Seema while swimming. Work is done whenever the given two conditions are satisfied: When a satellite moves around the Earth, then the direction of force of gravity on the satellite is perpendicular to its displacement. Therefore, its kinetic energy becomes 4 times its original value, because it is proportional to the square of the velocity. We have Provided Work and Energy Class 9 Science MCQs Questions with Answers to help students understand the concept very well. Q72: Define kinetic energy. = ½ mv 2. 1 kWh = 3.6 x 106 J It is further classified into gravitational potential energy (GPE) and elastic potential energy … Work and Energy Kinetic Energy . Write an expression for the kinetic energy of an object. F= 7 N Therefore we can say that kinetic energy is: The derivation of kinetic energy using calculus is given below. Q12 : Can there be displacement of an object in the absence of any force acting on it? Q3 : A battery lights a bulb. Answer : Hence, work is done by the wind mill in lifting water from the well. What will be its kinetic energy when its velocity is doubled? Kinetic Energy: The kinetic energy of an object moving with a certain velocity is the work done on the object to acquire that velocity. Write an expression for the kinetic energy of an object. Also, there is no loss of energy because muscular energy is transferred into heat energy, which causes our body to become hot. Answer : This is the formula of Kinetic energy of an object of mass m moving with speed v along a line. Substituting in eq n 1, we get, W = 1/2 mv 2. of body will also be zero.Kinetic energy is a scalar quantity like other forms of energies. • A wind mill is lifting water from a well. (ii) There is a displacement of the body caused by the applied force along the direction of the applied force. Work, Power And Energy Class 9 Extra Questions Short Answer Type 2. Answer: Expression for kinetic energyis m = Mass of the object v = Velocityof the object = 5 m s−1 Given that kinetic energy, = 25 J (i) If the velocityof an object is doubled, then v = 5 × 2 = 10 m s−1. W= F x s. Q5 : Define 1 J of work. When a bulb is connected to a battery, then the chemical energy of the battery is transferred into electrical energy. Expression for kinetic energy is Kinetic energy - The energy possessed by virtue of its motion is said to be kinetic energy. Let us take it that the force acts on the object through the displacement. The Questions and Answers of Mathematical expression of kinetic and potential energy are solved by group of students and teacher of Class 9, which is also the largest student community of Class 9. K = 1 2 m u 2. Q20 : Find the energy in kW h consumed in 10 hours by four devices of power 500 W each. W= 140 x 15 = 2100 J Kinetic energy of an object of mass, mmoving with a velocity, vis given by the expression, is the kinetic energy. Your email address will not be published. Hence, the work done by gravity on the body is zero. (g)Wind energy applies a force on the sailboat to push it in the forward direction. v 2 = 2as. Answer: K.E. Obtain an expression for the kinetic energy of an object. "Energy posses by a body by virtue of its motion is referred to as 'Kinetic Energy'". Write an expression for the kinetic energy of an object. Answer : Where is the energy you spend going? Question From class 9 Chapter WORK AND ENERGY Write an expression for kinetic energy of an object. ... Write an expression for the kinetic energy of an object Answer Kinetic energy of an object = ½ mv 2 Where m = Mass of object v = Velocity of object Subscribe to our Youtube Channel - … Answer : Therefore, energy consumed = Power x Time 1 unit = 1 kWh Work and Energy Class 9 Notes | NCERT Chapter 11 Explanation, Video, Question Answers. • A green plant is carrying out photosynthesis. Q2 : An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. Average power is obtained by dividing the total amount of work done in the total time taken to do this work. 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