Velocity of car after 180 degree turn

In summary, the conversation discusses the concept of velocity and its change in a specific scenario where a car is traveling east at 60km/h and then changes direction to travel west at the same speed. The question asks for the change in velocity, which is determined by subtracting the initial velocity from the final velocity. It is also mentioned that using vectors is a better way to solve such problems.
  • #1
ujellytek
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Imagine a car is traveling east 60km/h, then after leaving the curve it's velocity is 60km/h west, what's it's change in velocity?
 
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  • #2
What do you think?
 
  • #3
Doc Al said:
What do you think?
I thought it was 0km/h but it was marked wrong, I just want to understand why.
 
  • #4
ujellytek said:
I thought it was 0km/h but it was marked wrong, I just want to understand why.
Recall that velocity is a vector: direction matters. (If they had asked for the change in speed, then that would be zero.)
 
  • #5
Doc Al said:
Recall that velocity is a vector: direction matters. (If they had asked for the change in speed, then that would be zero.)
Can you explain how to solve this?
 
  • #6
Choose a sign convention. Let's say east is positive and west is negative.

Given that, what would be the initial and final velocities, including their sign?
 
  • #7
Doc Al said:
Choose a sign convention. Let's say east is positive and west is negative.

Given that, what would be the initial and final velocities, including their sign?
v1=60 km/h [E] v2=60 km/h [W] ? *delta*v=??
 
  • #8
ujellytek said:
v1=60 km/h [E] v2=60 km/h [W] ? *delta*v=??
Instead of E & W, use + and -.

v1 = + 60 km/h
v2 = ?
 
  • #9
Doc Al said:
Instead of E & W, use + and -.

v1 = + 60 km/h
v2 = ?
I have no idea what to do
 
  • #10
ujellytek said:
I have no idea what to do
If the initial velocity (to the east) is + 60, what must the final velocity (to the west) be?
 
  • #11
Doc Al said:
If the initial velocity (to the east) is + 60, what must the final velocity (to the west) be?
-120, thanks I get it now
 
  • #12
ujellytek said:
-120, thanks I get it now
Good. The change in velocity is 120 km/h to the west.
 
  • #13
Just a follow up comment on this, it is always a good idea to use vectors. While + and - works for this problem where the velocities are along the same line, using vectors is a better and more general way to solve it.

The question asks for the difference or change in velocity. One must subtract the initial velocity from the final velocity to determine the change in velocity:
##\vec{\Delta{v}} = \vec{v_f} - \vec{v_i}##

If, like me, you find vector subtraction to be a bit confusing, you can easily turn it into a vector addition equation:
##\vec{v_f} = \vec{v_i} + \vec{\Delta{v}}##

You want to find ##\vec {\Delta{v}}##. If you draw ##\vec{v_f} \text{ and } \vec{v_i}## tail to tail and then ask your self "what vector added to the initial velocity vector (ie. its tail touching the arrow of the initial velocity vector) results in the final velocity vector?" (ie. its arrow touches the arrow of the final velocity vector) you will have your answer. Since the change in velocity is a vector you must specify its direction as well as its magnitude (ie. its length which represents speed).

AM
 
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  • #14
With vector problems, ALWAYS draw the triangle or whatever figure.
 

FAQ: Velocity of car after 180 degree turn

1. What is the velocity of a car after making a 180 degree turn?

The velocity of a car after making a 180 degree turn depends on various factors such as the initial velocity, radius of the turn, and the friction between the tires and the road surface. It is not possible to provide a specific answer without knowing these variables.

2. Does the weight of the car affect its velocity after making a 180 degree turn?

Yes, the weight of a car can affect its velocity after making a 180 degree turn. A heavier car will have more inertia and require more force to change its direction, resulting in a lower velocity after the turn compared to a lighter car.

3. Can a car maintain the same velocity after making a 180 degree turn?

In theory, a car can maintain the same velocity after making a 180 degree turn if there is no external force acting on it. However, in reality, factors such as friction and air resistance will cause a decrease in velocity after the turn.

4. What is the difference between velocity and speed in the context of a 180 degree turn?

Velocity is a vector quantity that includes both speed and direction, while speed is a scalar quantity that only measures the rate of motion. In the context of a 180 degree turn, velocity takes into account the change in direction, while speed only measures the change in distance traveled.

5. How does the velocity of a car change before and after a 180 degree turn?

Before the turn, the car's velocity will depend on its initial speed and direction. During the turn, the velocity will change as the car's direction changes. After the turn, the car's velocity will be different from its initial velocity due to factors such as friction and air resistance.

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