Change in momentum after hitting a wall

AI Thread Summary
The discussion revolves around calculating the change in momentum when a 1.0 kg ball traveling at 4.0 m/s strikes a wall and bounces back at 2.0 m/s. The correct answer for the change in momentum is determined to be 6 kg m/s, corresponding to option C. The user initially miscalculated the change in momentum as 2 kg m/s, not accounting for the direction of the velocities. The importance of considering the sign associated with velocity in momentum calculations is emphasized. This highlights a common error in physics problems involving momentum and direction.
gake
Messages
12
Reaction score
0

Homework Statement



32) The change in momentum, in kg m/s, that occurs when a 1.0 kg ball traveling at 4.0 m/s strikes a wall
and bounces back at 2.0 m/s is
A) 2.
B) 4.
C) 6.
D) 8.
Answer: C

Homework Equations



Momentum==Mass*Velocity

The Attempt at a Solution



I get A.

Momentum1==1*4
Momentum2==1*2

Momentum1-Momentum2==2
 
Physics news on Phys.org
Consider the "sign" associated with the two velocities.
 
What a dumb mistake! Thanks :)
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Ambiguous question on momentum and how it works...
Replies
13
Views
1K
Work done during a collision -- Change in Kinetic Energy & change in Momentum
Replies
1
Views
2K
How Does Impulse Relate to Momentum Change in Physics Problems?
Replies
7
Views
2K
Conservation of momentum (wrecking ball hits a stationary object)
Replies
10
Views
3K
Golf club 🏌️and ball ⛳ impulse problem
Replies
19
Views
2K
Find Mass 2 with Momentum Conservation
Replies
9
Views
3K
Momentum in different referance frames
Replies
6
Views
2K
Change in momentum when given the speed (not the velocity).
Replies
2
Views
3K
Which Force is Represented by the Gradient of the Ball-Wall Collision Graph?
Replies
3
Views
4K
Change in momentum for a satellite in circular orbit
Replies
6
Views
3K

Hot Threads

Recent Insights

Back
Top