Pushing a stalled car out of an intersection

Click For Summary
SUMMARY

The discussion focuses on the physics of pushing a stalled car out of an intersection, specifically using impulse and momentum principles. The user calculated the impulse as 11076 Ns, leading to a final velocity of 11.48 m/s for a car weighing 965 kg. The conversation emphasizes the need to analyze the motion in both x and y components and suggests using kinematic equations to determine acceleration and displacement. The user is encouraged to clarify whether the calculated force is the net force acting on the car.

PREREQUISITES
  • Understanding of impulse and momentum concepts
  • Familiarity with kinematic equations
  • Ability to create and interpret free body diagrams
  • Basic knowledge of vector components in physics
NEXT STEPS
  • Study the relationship between impulse and momentum in detail
  • Learn how to apply kinematic equations for motion analysis
  • Explore the concept of net force and its implications in dynamics
  • Review examples of free body diagrams in real-world scenarios
USEFUL FOR

Physics students, automotive engineers, and anyone interested in understanding the dynamics of vehicle motion and force application in practical situations.

carodog
Messages
1
Reaction score
0
Homework Statement
A student is attempting to push his stalled car out of an intersection with his girlfriend at the wheel. The car and girlfriend has a combined mass of m = 965 kg. Unfortunately the hill has an incline of θ = 2.2 degrees with respect to the horizontal. The student can supply a force of F = 852 N for t = 13 s before tiring. What is the furthest the edge of the intersection can be (d) in meters from the stalled car in order to make it out in one push? Assume no rolling resistance from the car and that his girlfriend brakes to bring the car to a stop when he stops pushing.
Relevant Equations
m = 965 kg
θ = 2.2 degrees
F = 852 N
t = 13 s
Hints given:
-Start with free body diagram. Use the relationship between impulse and momentum to find the final velocity of the car after he has pushed for time t.
-Use a kinematic equation to relate the final velocity and time to the distance traveled.
-What is his initial velocity?

My attempt:
Impulse = F (delta t) = change in momentum = 852N (13s) = 11076 Ns

Initial momentum = 0 Ns
Final momentum = 11076 Ns = mv = (965kg) v
Final velocity v = 11.48 m/s

Not sure where to go from here. Thinking maybe I should be splitting things up into x- and y- components and then using the v-t relation: delta v = a (delta t). If initial velocity is 0 (braking) then I could solve for acceleration and then use x-t relation: (delta x) = (initial v)(delta t) + (.5a(delta t)^2) to find displacement...
 
Physics news on Phys.org
carodog said:
Impulse = F (delta t) = change in momentum
Only if that is the net force.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 54 ·
2
Replies
54
Views
5K
Replies
10
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 12 ·
Replies
12
Views
2K