How Does Conservation of Momentum Determine Speed After a Collision?

In summary, the combined speed of the woman and skateboard is 9.25m/s. The mass of the woman is 44kg and the skateboard is 30kg, and the woman is running at a speed of 8m/s.
  • #1
Crichar1
7
0
A woman with a mass of 44 kg runs at a speed of 8 m/s and jumps onto a giant 30 kg skateboard initially at rest. What is the combined speed of the woman and the skateboard?

44 kg / 8 m/s=5.5
30 kg / 8m/s=3.75

5.5+3.75=9.25m/s
 
Physics news on Phys.org
  • #2
What do you know about mechanics that will help? Any equations?

The Bob
 
  • #3
Think momentum.
 
  • #4
i tried the linear momentum equation..mass * velocity and the answer was still incorrect
 
  • #5
But what did you do to get this incorrect answer?

The Bob
 
  • #6
mass x velocity

44kg x 8m/s= 352

30kg x 8m/s=240

352-240=112m/s

didn't seem right but i thought i would try it anyways
 
  • #7
Right, now I see what you're doing. Have you heard of something called 'conservation of momentum'? Basically, the momentum before a 'change' must be equal to the combined momentum afterwards. You've, therefore, wrongly assumed that the skateboard has velocity of 8ms-1.

So... try imagining the woman and the skateboard as one mass after they have 'combined'.

The Bob
 
  • #8
Crichar1 said:
i tried the linear momentum equation..mass * velocity and the answer was still incorrect

Conservation of momentum. The total momentum before she jumps on the board=total momentum after she jumps on the board.
 

FAQ: How Does Conservation of Momentum Determine Speed After a Collision?

What is the magnitude of average force?

The magnitude of average force is a measure of the strength of a force exerted on an object over a period of time. It is calculated by dividing the total force by the duration of the force.

How is the magnitude of average force different from instantaneous force?

The magnitude of average force represents the average strength of a force over a period of time, while instantaneous force refers to the strength of a force at a specific moment in time.

What is the unit of measurement for magnitude of average force?

The unit of measurement for magnitude of average force is Newtons (N), which is equivalent to kg*m/s^2.

How can the magnitude of average force be calculated?

The magnitude of average force can be calculated by dividing the change in an object's momentum by the time interval during which the force was applied.

Why is the magnitude of average force important in physics?

The magnitude of average force is an important concept in physics because it helps us understand the impact of forces on objects and how they affect their motion. It is also a key factor in determining the work and energy involved in a physical system.

Similar threads

Replies
6
Views
7K
Replies
23
Views
2K
Replies
2
Views
2K
Replies
2
Views
7K
Replies
10
Views
3K
Replies
1
Views
3K
Back
Top