Force of Friction: Calculating Car's Acceleration

AI Thread Summary
To calculate the average force of friction on a 1200 kg car that coasts to a stop from 30 m/s in 40 seconds, first determine the car's acceleration by dividing the change in speed by the time taken. The acceleration is negative, indicating deceleration, which can be calculated as the speed change over 40 seconds. Once the acceleration is found, apply Newton's second law (F = ma) to find the force of friction acting on the car. This force is responsible for the car's deceleration until it comes to a stop. Understanding these calculations is crucial for solving the problem effectively.
elissadi
Messages
10
Reaction score
0
I'm stuck! Please help! I have been looking @ this problem for 2 hours! :rolleyes:
A 1200 kg car has a speed of 30 m/s - it runs out of gas and coasts, stopping in 40 secs. What is average force of friction on the car?
Do you find the car's acceleration first? There is no force, so you can't use a=F/m
 
Physics news on Phys.org
You should be able to find the acceleration. Acceleration is the change of speed divided by the time taken. You know the time, how about the speed?
 
You get the acceleration by using the speed divided by 40 seconds.
 
Ok...

Ok, thanks...I found the acceleration, now how does that fit into the rest of the situation?
 
The friction force causes the acceleration of that mass (car). Use F = ma.
 
find the deceleration, then apply the eqn F=ma
 
Thread 'Voltmeter readings for this circuit with switches'

Thread 'Voltmeter readings for this circuit with switches'

TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
View full post »
Thread 'Correct statement about a reservoir with an outlet pipe'

Thread 'Correct statement about a reservoir with an outlet pipe'

The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
View full post »

Similar threads

Angular velocity- A toy train rolls around a horizontal track
Replies
8
Views
794
Friction force on a ball falling through a body of water
Replies
9
Views
1K
Coefficient of Friction question for a cart going down a wooden ramp
Replies
18
Views
3K
Calculation of Box's Acceleration on a Trailer with Friction
Replies
9
Views
2K
Forces when car wheels "lay rubber"
Replies
5
Views
2K
Calculating Force and Acceleration in a Two Block System with Varying Friction
Replies
6
Views
1K
How Do I Determine Force of Static Friction on a Rolling Car
Replies
15
Views
2K
How Do You Calculate Race Car Acceleration and Power Output?
Replies
20
Views
2K
Stopping distances on a downward slope
Replies
3
Views
2K
Constant frictional resistance & retardation
Replies
6
Views
1K

Hot Threads

Recent Insights

Back
Top