What is acceleration when velocity is maximum?

Text Solution

Velocity is maximum, whereas acceleration is zero.When velocity is maximum, its acceleration is maximumFor any value of v, the value of a is zeroWhen v is zero, a is also zero.

Answer : A

Solution : Particle of SHM have maximum velocity at mean position. So in `v= pm omega sqrt(A^(2)-x^(2)), x=0` <br> `therefore v= A omega` is maximum value of velocity and in acceleration `a= -omega^(2)x, x=0, a=0`.

The following is an exclusive excerpt from the book Developing Speed, published by Human Kinetics. All text and images provided by Human Kinetics.

Acceleration and maximum speed are terms used in speed development programs, and when developing a program, it is vital to differentiate between them. This allows coaches to target their training to the capacity most important in their own sport. Acceleration is the rate of change of velocity, or how quickly an athlete can increase the velocity of the motion. Maximum speed is the highest rate of speed an athlete can attain.

Acceleration refers to velocity, and because velocity has both a magnitude and direction associated with it, acceleration changes when athletes change the magnitude of their motion (how fast they are running), the direction of their motion, or both. In terms of running, anytime the body starts, speeds up, or changes direction, it is accelerating. Given the number of direction changes in most sports, together with the number of times the rate of velocity needs to change, then clearly acceleration plays a crucial role in speed performance in sport. This is further emphasized by the fact that elite sprinters have been shown to take up to 60 meters to reach top speed, and while this distance is normally shorter for field sport athletes, it still takes a considerable distance for most athletes to reach their maximum speed. Given the typical distances run in sport and the limits of court dimension in other sports, such as tennis and basketball, acceleration may play a more important role than maximum speed in these sports.

However, as chapter 2 demonstrates, maximum speed still plays an important role in sport because athletes can still reach a high proportion of their maximal speed in a relatively short distance. Figures from the International Associations of Athletics Federations have shown that during his 100 meter final in the Beijing Olympics, Usain Bolt achieved 73 percent of his maximum velocity at 10 meters, 85 percent at 20 meters, 93 percent at 30 meters, and 96 percent at 40 meters. He attained maximum speed at 60 meters. Therefore, developing maximum speed should still be included in the training for most sports, but the relative importance of the two should dictate the time spent on each.

While acceleration and maximum speed are two different qualities, acceleration is the process by which an athlete attempts to move toward maximum speed. For this reason, the process of acceleration goes through distinct phases. In the initial phase, an athlete’s velocity is low, and therefore the capacity to increase velocity is great. This is the pure acceleration phase, often referred to in track sprinting as the drive phase. However, as distance increases, athletes approach speeds far closer to their maximum, and this is the transition acceleration phase. For example, in the Usain Bolt figures listed earlier, at 30 meters Bolt had attained 93 percent of his maximum velocity, while at 10 meters he had only attained 73 percent. Thus, as distance increases, the capacity for further acceleration decreases. Similarly, the key technical features of acceleration differ at these stages.

With Developing Speed, the National Strength and Conditioning Association (NSCA) has created the definitive resource for developing speed training programs that optimize athletic performance. Including assessments and the application of speed training to eight specific sports, this authoritative guide provides all the tools needed for maximizing speed. The book is available in bookstores everywhere, as well as online at the NSCA Store.