Easy problem that I'm a bit confused about.

In summary, Joe and John are playing catch in space with Joe throwing the ball at a velocity of 7.5 m/s. Joe's mass is 60.9 kg, John's mass is 79.8 kg, and the ball's mass is 6.5 kg. The homework question asks to find the velocities of Joe and John after the catch. Using the equations for sum of external forces and Psys, the velocity of Joe after throwing the ball is calculated to be -0.72329 m/s, and the velocity of John after catching the ball is 0.56489 m/s. The problem is set up correctly.
  • #1

Homework Statement



You have Joe and John playing catch in space. Joe throws the ball to John with a velocity of 7.5 m/s.

Given Variables
Joe's mass is 60.9 kg
John's mass is 79.8kg
Ball's mass is 6.5kg

Find:
A) Joe's velocity after he throws the ball.
B) John's velocity after he catches the ball.

Homework Equations



Sum of the external forces = 0; Psys=0

For A, I used:
(Mass of ball+ Mass of Joe) (Velocity of Joe after he throws the ball) + (Mass of ball)(Velocity of Ball) = 0

I ended up with: Velocity of Joe after he throws the ball = - [(Mass of ball)(Velocity of ball)]/(Mass of Ball + Mass of Joe9)

After substituting in the numbers, the velocity of Joe is: -.72329 m/s

For B, I used:

(Mass of Ball)(Velocity of Ball) = (Mass of John + Mass of Ball)(Velocity of John after he catches the ball)

The Velocity of John after he catches the ball is: .56489m/s


Did I set this problem up properly?
Any suggestions or clarification would be greatly appreciated. Thanks.
 
Physics news on Phys.org
  • #2
Looks good to me.
 
  • #3




Yes, you set up the problem correctly. To find the velocities after the ball is thrown and caught, you must use the principle of conservation of momentum, which states that the total momentum of a closed system remains constant. In this case, the system is closed because there are no external forces acting on it.

Your equations for A and B are correct. However, there is a slight error in your calculations for A. The correct formula should be:

(Mass of ball x Velocity of ball) = (Mass of ball + Mass of Joe) x Velocity of Joe after throwing the ball

When you substitute the numbers, the velocity of Joe after throwing the ball should be 0.72329 m/s, not -0.72329 m/s. This means that Joe will have a velocity in the same direction as the ball after he throws it.

Overall, your approach and equations are correct. Just be careful with your calculations and make sure to double check them to avoid any errors. Good job!
 

What is the definition of an "easy problem" in science?

An "easy problem" in science refers to a problem or question that has a straightforward solution or answer. It is commonly used to describe problems that can be solved using existing knowledge and techniques without much difficulty.

Why do scientists encounter "easy problems"?

Scientists often encounter easy problems as they explore and investigate more complex and challenging questions. These simple problems can serve as building blocks for more complex research and help scientists gain a better understanding of a particular topic or phenomenon.

What are some examples of "easy problems" in science?

Examples of easy problems in science can include basic calculations, simple experiments with predictable outcomes, and identification of known substances or species. These problems may also arise during the initial stages of research projects as scientists gather information and data to form more complex hypotheses and questions.

How do scientists approach "easy problems"?

Scientists approach easy problems by using their knowledge and skills to analyze and solve the problem systematically. This may involve conducting experiments, making observations, or consulting existing research and data. They may also collaborate with other scientists to gain new perspectives and insights.

Can "easy problems" lead to significant scientific discoveries?

Yes, easy problems can lead to significant scientific discoveries. Sometimes, what may seem like a simple problem can reveal unexpected results or insights that can contribute to the advancement of scientific knowledge. It can also lead to the development of new techniques and methods that can be applied to more complex problems.

Suggested for: Easy problem that I'm a bit confused about.

Replies
4
Views
262
Replies
19
Views
5K
Replies
7
Views
805
Replies
5
Views
793
Replies
9
Views
745
Replies
4
Views
326
Replies
31
Views
400
Replies
3
Views
616
Back
Top