Do I need to calculate in car and trailer tension separately?

  • Thread starter lemon
  • Start date
In summary: I like your name. :wink:)In summary, a car with a mass of 1000kg towing a trailer with a mass of 650kg has an acceleration of 2.3m/s^2. The value of the external force between the wheels and the road is 2500N. The tension in the coupling between the car and the trailer is 200N for the car and 1005N for the trailer, with a total tension of 1205N.
  • #1
lemon
200
0
1. A car of mass 1000kg is towing a trailer of mass 650kg and the two have an acceleration of 2,3m/s^2. Assuming that the only external force is the driving force between the wheels and the road, calculate:
1: the value of this force
2: the tension in the coupling between the car and the trailer.

I'm a little unsure about this question. When it says 'external force', the driving force between the wheels and the road, it does just mean the driving force, right? And not the frictional force?
Also, my calculations for tension have come out at 0N. But I think there must still be a Tension/resultant force between the two vehicles as they are not moving at a constant velocity. Do I need to calculate in car and trailer tension separately?

2. F=ma
F-T=ma

3.
(a) F=(1000kg+650kg)2.3m/s^2
=2500N (2sf)
(b) F-T=ma
T=F-ma
T=2500-2500=0
 
Last edited:
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  • #2
Welcome to PF!

Hi lemon! Welcome to PF! :smile:

(try using the X2 tag just above the Reply box :wink:)
lemon said:
I'm a little unsure about this question. When it says 'external force', the driving force between the wheels and the road, it does just mean the driving force, right? And not the frictional force?

They're the same …

by good ol' Newton's third law, action is equal and opposite to reaction, so the (drive) force of the car on the road equals the (friction) force of the road on the car. :wink:
Do I need to calculate in car and trailer tension separately?

(b) F-T=ma
T=F-ma
T=2500-2500=0

Yes, you can only find T if it's an external force, so that means that you must consider only the forces on the car (or only the forces on the trailer).

(So your m in that last equation is wrong.)
 
  • #3
Welcome to PF!

Hi lemon! Welcome to PF! :smile:

(try using the X2 tag just above the Reply box :wink:)
lemon said:
I'm a little unsure about this question. When it says 'external force', the driving force between the wheels and the road, it does just mean the driving force, right? And not the frictional force?

They're the same …

by good ol' Newton's third law, action is equal and opposite to reaction, so the (drive) force of the car on the road equals the (friction) force of the road on the car. :wink:
Do I need to calculate in car and trailer tension separately?

(b) F-T=ma
T=F-ma
T=2500-2500=0

Yes, you can only find T if it's an external force, so that means that you must consider only the forces on the car (or only the forces on the trailer).

(So your m in that last equation is wrong.)
 
  • #4
Welcome to PF!

Hi lemon! Welcome to PF! :smile:

(try using the X2 tag just above the Reply box :wink:)
lemon said:
I'm a little unsure about this question. When it says 'external force', the driving force between the wheels and the road, it does just mean the driving force, right? And not the frictional force?

They're the same …

by good ol' Newton's third law, action is equal and opposite to reaction, so the (drive) force of the car on the road equals the (friction) force of the road on the car. :wink:
Do I need to calculate in car and trailer tension separately?

(b) F-T=ma
T=F-ma
T=2500-2500=0

Yes, you can only find T if it's an external force, so that means that you must consider only the forces on the car (or only the forces on the trailer).

(So your m in that last equation is wrong.)
 
  • #5
Hi:
So, to answer part b correctly:

Car: 2500N-T=1000kg x 2.3ms
T=2500N-2300N=200N

Trailer: 2500N-T=650kg x 2.3m
T=2500N-1495N=1005N

Total T=Tcar+Ttratiler=200N+1005N=1205N
 
  • #6
test
 
  • #7
ms-2
 
  • #8
lemon said:
Hi:
So, to answer part b correctly:

Car: 2500N-T=1000kg x 2.3ms
T=2500N-2300N=200N

Trailer: 2500N-T=650kg x 2.3m
T=2500N-1495N=1005N

Total T=Tcar+Ttratiler=200N+1005N=1205N

lemon said:
test

lemon said:
ms-2

Hi lemon! :smile:

I see you had the same problem as I did, with the server! :biggrin:

Your car equation is completely correct …

and you should have stopped there! :wink: :rolleyes:

Your trailer equation is wrong, because there's only one force on the trailer, and that's T.

F is a force on the car, not on the trailer … all the trailer gets is what comes through the coupling.

So you could have said T = mtrailera, which would give you the same result as F - T = mcara … either will do, but the first one is shorter. :wink:
 
  • #9
You rock! Roll! Rave!
Whatever.
Thanx
 

1. Do I need to consider the weight of my car and trailer separately when calculating tension?

Yes, it is important to calculate the tension of your car and trailer separately. The weight of the trailer adds additional stress on the car, which can affect its overall performance and safety.

2. How does the length of the trailer affect tension calculations?

The length of the trailer can affect tension calculations in two ways. First, a longer trailer will have more surface area and therefore may create more drag, increasing tension. Second, a longer trailer may also have a higher weight, which will also increase tension on the car.

3. Can I use the same tension calculation for different types of trailers?

No, different types of trailers may have different weights and lengths, which will affect tension calculations. It is important to adjust your calculations based on the specific type of trailer you are using.

4. Should I consider the road conditions when calculating tension?

Yes, the road conditions can play a significant role in the tension on your car and trailer. For example, driving on a bumpy or uneven road may cause more tension on the trailer, while driving on a smooth road may result in less tension.

5. Is it necessary to recalculate tension during a long trip?

Yes, it is recommended to recalculate tension during a long trip, especially if you encounter different road conditions or make changes to the weight of your trailer. This will ensure that your car and trailer are operating safely and efficiently.

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