Shot put throw During a practice shot put throw, the 7.0 -kg shot left world champion C . J. Hun

Shot put throw During a practice shot put throw, the 7.0 -kg...

Key Concepts

Uniform Acceleration Assumption

The assumption of uniform acceleration simplifies the analysis by allowing the use of kinematic equations. When the acceleration is constant, one can easily relate displacement, initial velocity, final velocity, acceleration, and time. This assumption is critical in problems where details of the force application (such as variations in acceleration) are not provided, enabling concrete calculations based on average values.

Impulse-Momentum Relationship

The impulse-momentum relationship connects the impulse (the product of force and the time over which it is applied) to the change in momentum of an object. This is important when considering how a force applied over a short period can result in the observed change in velocity, making it possible to explore the dynamics of the pushing phase in throws or similar actions.

Force

Force is the interaction that causes an object to accelerate. When a force is applied over a distance, it performs work on the object. By using the distance over which the force is applied and the change in kinetic energy, it is possible to estimate the average force exerted. This concept is fundamental in mechanics to connect how actions at the point of contact result in changes in the motion of objects.

Kinetic Energy

Kinetic energy is the energy that an object possesses due to its motion. It is defined as one half of the mass times the square of its velocity. In contexts like throw events or other projectile motions, knowing the kinetic energy allows one to compute how much work was required to reach a certain speed, assuming energy is transferred from the applied force.

Work-Energy Theorem

The work-energy theorem states that the work done on an object is equal to the change in its kinetic energy. It is a fundamental concept in mechanics that allows us to relate the force applied over a distance (the work) to the resulting speed of an object. This concept is useful in scenarios where an object is accelerated over a known distance from rest, as the initial kinetic energy can be calculated to determine the work done by the applied force.

Transcript

00:01 All right, so during a practice shot put throw, the seven kilogram shot left world champion, c .j.

00:07 Hunter's hand, at a speed of 13 meters per second.

00:10 While making the throw, his left hand pushed the shot a distance of 1 .7.

00:13 Okay, so our final velocity, and let's just assume, let's make this really simple.

00:19 This thing's going to accelerate in the x direction.

00:22 Okay.

00:22 I know that it's more complicated than that, right? there's really actually kind of an angled upward, but let's just pretend that they're accelerating this thing.

00:29 We're accelerating this in the x direction, right? and the final velocity is 13 meters per second.

00:38 And then they're saying that the distance is 1 .7 years, right? so this means that that is the changing position, right? so x minus x -0.

00:50 Okay.

00:51 And they want to describe all the physical quantities you can determine using this information.

00:55 So let's just wow them here.

00:57 Okay.

00:59 If we're figuring this out, right, what i want to do is i think we can figure out the force, we can figure out the average acceleration, right? we could find the average velocity.

01:08 Let's do that first, right? so our average velocity is going to just be the initial velocity plus the final velocity, right, divided by two.

01:18 Okay? so this guy is going to be what, let's assume, we're assuming that it starts at zero, right? this is one of my assumptions is, right? okay, so that's one of my assumptions, right? assumptions.

01:37 That it all happens in the x direction, that the initial velocity in the x direction is zero.

01:45 All right, those are some assumptions.

01:47 I'm keeping track so far, right? okay, so this is zero plus 13 divided by two.

01:53 So our average velocity is going to be 6 .5 meters per second.

01:59 Okay, and that's what that means.

02:01 A little v bar means average, right? i could write average two.

02:04 Okay.

02:05 So that's our average velocity.

02:07 Let's figure out the acceleration.

02:10 All right.

02:10 The average acceleration, i'm going to use equation 1 .7, okay? which says that two times the acceleration in the x direction times the displacement in the x direction, right? this is just the change in distance, right? so that'll be our 1 .7 meters...

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