You throw a ball upward. (a) Draw a motion diagram and two...

Name: Problem 6, Chapter 2: College Physics
Uploaded: 2020-04-05T22:07:35-08:00
Duration: 4 min 37 s
Channel: Chris Murray
Description: You throw a ball upward. (a) Draw a motion diagram and two force diagrams for the ball on its way up and another motion diagram and two force diagrams for the ball on its way down. (b) Represent the motion of the ball with a position-versus-time graph and velocity-versus-time graph.

You throw a ball upward. (a) Draw a motion diagram and two force diagrams for the ball on its way up and another motion diagram and two force diagrams for the ball on its way down. (b) Represent the motion of the ball with a position-versus-time graph and velocity-versus-time graph.

Key Concepts

Velocity versus Time Graph

A velocity versus time graph shows the relationship between an object's velocity and time. In scenarios involving constant acceleration due to gravity, this graph is characterized by a straight line with a negative slope, reflecting the decrease in upward velocity to zero at the peak and the increase in downward velocity during descent.

Position versus Time Graph

A position versus time graph is used in kinematics to represent how the displacement of an object changes over time. It typically shows curves in cases of constant acceleration (such as gravity), indicating how an object ascends, momentarily pauses at its peak, and then descends.

Free Body Diagrams

Free body diagrams illustrate all the forces acting on an object at a given moment. In mechanics, particularly in projectile motion, such diagrams are crucial in identifying forces like gravity that affect the acceleration and overall motion of the object.

Motion Diagrams

Motion diagrams are simplified visual representations where the positions of an object are marked at evenly spaced time intervals. They help in visualizing the speed and acceleration of an object by the spacing of the markers—wider spacing indicates faster motion while narrowing spacing indicates slowing down.

Transcript

00:01 So we're going to throw a ball upward.

00:03 And we want to draw a motion diagram and two force diagrams for the ball on its way up.

00:07 Another motion diagram and two force diagrams for the ball on its way down.

00:13 Represent the motion of the ball with a position versus time graph and a velocity versus time graph.

00:19 Okay.

00:20 So let's just take a look at this.

00:21 This ball is going to go up and it's going to go down.

00:25 Okay.

00:26 So let's just draw a picture of this.

00:29 We've got the ball here.

00:30 Let's draw the, let's draw our velocity.

00:35 So it starts off going fast.

00:37 In the next instance, it's not going quite as fast, slower and slower until eventually it reaches the top.

00:45 And it's not moving, right? and then on the way down, it's going to be, it's going to be, it's going to be going to be going to be going to be going to be going to be going to be going to be going down a little faster, down a little faster.

01:00 And in general, it's going to go down and hit the ground going at the same speed, but it in the opposite, direction.

01:06 So if we look at the velocities, right? on the way up, it's accelerating down.

01:11 On the way down, it's accelerating down.

01:14 Notice that it's going slower and slower on the way up, but the direction of the acceleration for both of these, the acceleration is going to be down.

01:21 This is, of course, the acceleration of earth's gravity.

01:25 So, and then if we look at the forces acting on it, as soon as it leaves your hand, presumably, like this is the instant it leaves your hand, as soon as it leaves your hand, the force is acting on this thing, or just the force that the earth is exerting.

01:42 So here's the ball on its way up.

01:47 The force that the earth is exerting is downward, right? here on the way up here, it's still that downward force.

01:54 And that force never changes.

01:56 It's uniform...

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