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Question 25 Short/Long Answer Questions Next
Answer:
Solution: Kinetic energy = \frac{1}{2}\times mass\times\left(velocity\right)^2 Since speed is doubled, its square will become 4 times. Hence, kinetic energy increases by 4 times.
Video transcript "Welcome to Reno learnings question-and-answer videos. My name is Penelope and I teach math and science than Dido. Let's have a look at this. A very interesting question in front of us but is a cyclist doubles his speed. So let's say this is our happy size list moving with speed V. And over here are cyclists a cyclist has changed your speed to double that is 2 V. This is the speed. This is the speed and here to V is the speed of this particular cyclist. Okay, let's read the question again. So as I said double his face then how will his scientific energy change so we have to see what will happen to the kinetic energy whether it will increase and it will decrease or whether it will remain the same. Okay before going to buy the energy we should all know what we mean by the energy in general. So energy is the capacity of a body. So do work. So energy is the capacity to do work is the SI unit is June jewel is the SI unit. It is also written as J, right. Okay. Now, let's move ahead with the kind of energy. What do we mean by kind of energy? So energy possessed by the body due to its motion. So in both these cases, the body is moving, right? That is the cycle is moving there for both of them have some kind of energy right? Let's say since it is the same side to the He has done just the wind velocity of the or doubles the speed of his riding exciting. Right? So let's say we will say that the mass of the cycle in that is Market the rider and cycle both will be thing M because he is writing the same title only the speed has changed. Okay. Now let's define. How do we express kinetic energy? So kinetic energy is expressed as half m v quit Where m is the mass of the body V is the velocity of the body. Let's write that down over here. So kind tick energy is equal to half MV square m is V is velocity. Now, let's look at him a first so case a let's calculate the kinetic energy when the cycle is moving at speed V. So kind big energy is equal to half. I've seen this. Okay. That's how I look at it be no. So we are looking at case be very precise with touch W speed so the kind of energy for B. So this is kind of energy and this is Bobby. So for B, it will be half now Mark is again the same because he is the same Rider. He's the same size since having the same cycle. Someone doesn't change half M. But here the velocity has System so we write to be square. So we see that half the solid further em into 4 V square or this cancels out with this so it becomes Or let's not cancel it. In fact, then it will be easier to say what will be the binding energy, right so over here this will become half M and there are two squares that you get some for. Let's keep it outside. So 4 into half m v squared or 4 will keep it outside 1/2 M VB squared. This is the kinetic energy to be Now how can this clever kind of energy of a right? So kind of energy of X can take the energy of a so clearly the chi chi chi energy has increased when the cyclist has doubled his feet and it has become for teaching afraid of kinetic energy. So kinetic energy has in Europe This is the answer to this question. I hope also have understood this it is any further questions. Please put your comments below. Thank you." > Solution final velocity = 5 m/s initial velocity = 2 m/s mass= 20 kg final kinetic energy = (1/2)*mass* (final velocity)^2 final KE = 0.5*20*5^2 = 10*25 = 250 J initial KE = (1/2)* mass* (initial velocity)^2 initial KE = 0.5*20*2^2 = 10*4 = 40 J according to work energy theorem work done = change in kinetic energy = Final KE - initial KE work done = 250 J -40 J work done = 210 J answer is 210 J thanks for asking.
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How much work was done to increase the kinetic energy of the bicyclist
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