How do I calculate the work done by gravity on a tossed ball?

In summary, a 0.267 kg ball is thrown straight up from 2.33 m above the ground. Its initial vertical speed is 12.00 m/s. A short time later, it hits the ground. The force of gravity does negative work on the ball as it moves upwards, and positive work as it moves downwards.
  • #1
Staerke
12
0
Hey all, I'm an idiot when it comes to algebra/physics/anything with numbers so you'll probably be seeing me around a lot until the end of the semester, but I'll try to lend aid when I can
Anyway, this is what I've got:

Homework Statement


A 0.267 kg ball is thrown straight up from 2.33 m above the ground. Its initial vertical speed is 12.00 m/s. A short time later, it hits the ground. Calculate the total work done by the force of gravity during that time.


Homework Equations



Force due to gravity = m * g

Height of trajectory = V^2 / 2 * g

Force = mass * distance (No Cos(theta) here because it's a straight up and down trajectory, right?)


The Attempt at a Solution



So, I figured the force of gravity working on the ball:
F = mg = 2.62 N = .267 * 9.81

Trajectory height = V^2 / 2 * g = 7.74866 = 12.33^2/(2*9.81)

Then I added 2.33 to the (7.75*2) (that's the distance up and down) which ended up being 17.83
Then used Force = Mass * Distance to get 46.689 Joules for an answer and apparently it's wrong, and I have no clue what to do.


I'm sure there's just a hole in my logic somewhere. Thanks for any help.
 
Physics news on Phys.org
  • #2
[tex]Work = F \cdot s[/tex]

The dot product makes all the difference. Recall also the definition of work: the work done by a force on an object is the product of the force and the displacement of the body in the direction of the force.

Thus, when the ball is moving upwards, gravity does negative work on the ball. When it is moving downwards, gravity does positive work on the ball.
 
  • #3
Fightfish said:
[tex]Work = F \cdot s[/tex]

The dot product makes all the difference. Recall also the definition of work: the work done by a force on an object is the product of the force and the displacement of the body in the direction of the force.

Thus, when the ball is moving upwards, gravity does negative work on the ball. When it is moving downwards, gravity does positive work on the ball.

Fantastic, I put 0 as total work done once, forgetting about the 2.33 M that it fell past where it started. Got the answer, thanks for your help!
 

Related to How do I calculate the work done by gravity on a tossed ball?

1. What is the definition of work done in relation to a tossed ball?

The work done in relation to a tossed ball is the amount of force that is required to move the ball from one point to another. It is a measure of the energy that is transferred to the ball as it is being thrown or caught.

2. How is work done calculated for a tossed ball?

The work done for a tossed ball is calculated by multiplying the force applied to the ball by the distance the ball travels in the direction of the force. This can be represented by the formula W = F x d, where W is work, F is force, and d is distance.

3. Does the force of gravity have an effect on the work done for a tossed ball?

Yes, the force of gravity does have an effect on the work done for a tossed ball. As the ball is tossed and caught, gravity is constantly acting on it, causing it to accelerate towards the ground. This acceleration increases the amount of work required to move the ball.

4. How does the height of a toss affect the work done for a tossed ball?

The height of a toss has a direct impact on the work done for a tossed ball. The higher the ball is thrown, the greater the distance it will travel and the more work will be required to move it. This is because the force of gravity will have more time to act on the ball, causing it to accelerate and travel a longer distance.

5. Is the work done for a tossed ball always the same regardless of how it is thrown or caught?

No, the work done for a tossed ball can vary depending on how it is thrown or caught. For example, if the ball is thrown with more force, it will require more work to move it. Similarly, if the ball is caught with more force, it will require more work to stop its motion. Additionally, the angle at which the ball is thrown or caught can also affect the work done.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
12
Views
572
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
2
Replies
38
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
3K
  • Introductory Physics Homework Help
Replies
14
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
12
Views
2K
Back
Top