How Do You Calculate Stopping Distance and Time with Kinetic Friction?

  • Thread starter Thread starter cbrons
  • Start date Start date
  • Tags Tags
    Friction
AI Thread Summary
To calculate stopping distance and time for a car braking from 20 m/s with a coefficient of kinetic friction of 0.1, one can use the principles of energy conservation and the work-energy theorem. The work done by friction equals the change in kinetic energy, allowing for the determination of stopping distance. The book indicates that both distance and time to stop are 200 m and 20 s, respectively. However, there is confusion about how to derive these values from the given information. Clarifying the application of these physics concepts can help solve the problem accurately.
cbrons
Messages
44
Reaction score
0

Homework Statement



1. A car moving at 20 m/s brakes and slides to a stop. If the coefficient of kinetic friction between the pavement and the tires of the car is 0.1, how far does the car slide?

A. 50 m
B. 100 m
C. 200 m
D. 400 m

2. A car moving at 20 m/s brakes and slides to a stop. If the coefficient of kinetic friction between the pavement and the tires of the car is 0.1, how much time is needed for the car to come to a complete stop?

A. 1 s
B. 10 s
C. 20 s
D. 40 s


Homework Equations



U(k)mgcos0

The Attempt at a Solution



Well the answers for both are C, as the back of the book states. The problem is, I don't understand how you can figure out either the time or distance with the information given... can anyone shed some light?
 
Physics news on Phys.org
Use energy conservation for the first one, the work done by friction is the change in kinetic energy.
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Coefficient of Friction question for a cart going down a wooden ramp
Replies
18
Views
3K
Help with question on motion: Avoiding a rear-end collision
Replies
6
Views
3K
Physics homework help needed -- A mass sliding down a ramp with friction
Replies
14
Views
3K
Stopping distances on a downward slope
Replies
3
Views
2K
Car Crash Analysis: Analyzing Friction & Speed
Replies
9
Views
4K
Stopping distance and static friction
Replies
1
Views
4K
How to find coefficient of friction *Without* mass?
Replies
3
Views
22K
Stopping Distance and kinetic friction
Replies
3
Views
2K
Kinetic energy & Conservation of energy
Replies
17
Views
2K
Calculating Kinetic Friction Coefficient for Sliding Soccer Player
Replies
13
Views
2K

Hot Threads

Recent Insights

Back
Top