What is the required impulse to bring the car to rest?

  • Thread starter Thread starter freeofwork
  • Start date Start date
  • Tags Tags
    Impulse Negative
Click For Summary
SUMMARY

The impulse required to bring a car with a mass of 1.0 x 103 kilograms moving at a speed of 1.4 x 102 m/s to rest is calculated to be 1.4 x 105 N·s. It is essential to note that this impulse is technically negative, as it acts in the opposite direction to the car's positive velocity. The discussion emphasizes the importance of recognizing the vector nature of impulse and momentum, where the direction of the force applied must be considered.

PREREQUISITES
  • Understanding of impulse and momentum concepts
  • Familiarity with Newton's laws of motion
  • Basic knowledge of vector quantities
  • Ability to perform calculations involving mass and velocity
NEXT STEPS
  • Study the relationship between impulse and momentum in detail
  • Learn about vector representation in physics
  • Explore real-world applications of impulse in automotive safety
  • Investigate the effects of varying mass and speed on required impulse
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, as well as educators and anyone interested in understanding the principles of impulse and momentum in automotive contexts.

freeofwork
Messages
44
Reaction score
0

Homework Statement


A car with a mass of 1.0 X 103kilograms is moving with a speed of 1.4 X10 2m/s. The impulse required to bring the car to rest is?


Homework Equations



impulse = change in momentum...

The Attempt at a Solution


the answere is 1.4 X 105 N X S or is it the negative...
 
Physics news on Phys.org
Technically the impulse must be negative to stop the positive velocity.
But it is so obvious that the minus sign is often omitted in reporting the answer. Like getting a bill for car repairs of $250. Your payment should really be -$250 to cancel it out, but we never bother saying that.

Velocity is usually defined as being a vector, so you are aware of its direction. But speed is not a vector, only the magnitude of velocity so when asked for speed no sign or direction is required. Impulse, acceleration and momentum don't have separate words for the magnitude so it often isn't clear whether the question requires a sign indicating direction. Both kinds of answer should be accepted in the absence of clarity.
 

Similar threads

Horizontal impulse on a ball at rest on a plane (with friction)
  • · Replies 14 ·
Replies
14
Views
3K
Momentum and impulse of a football
  • · Replies 2 ·
Replies
2
Views
2K
Work done during a collision -- Change in Kinetic Energy & change in Momentum
  • · Replies 1 ·
Replies
1
Views
2K
A misconception I have about impulse formula interpretation
  • · Replies 2 ·
Replies
2
Views
2K
How does changing the duration of a collision affect impulse
  • · Replies 1 ·
Replies
1
Views
2K
Net impulse and what objects exerts force
  • · Replies 4 ·
Replies
4
Views
4K
Pushing a stalled car out of an intersection
  • · Replies 1 ·
Replies
1
Views
2K
Impulse imparted to A by B during collision
  • · Replies 7 ·
Replies
7
Views
4K
Impulse Question -- A car changing speed and direction
  • · Replies 7 ·
Replies
7
Views
2K
Calculating the magnitude of an impulse
  • · Replies 4 ·
Replies
4
Views
5K