Basic Kinematics - Initial Velocity

In summary, the conversation discusses a problem statement involving a truck driving from point A to point B, a distance of 180 meters, in 10 seconds with a constant deceleration rate of 6 meters per second squared. The initial velocity is being calculated, with conflicting answers between the asker and the solution manual. After further discussion, it is confirmed that the problem statement states a deceleration rate of -0.6 meters per second squared, and the solution manual has made a mistake by using a deceleration rate of -6 meters per second squared. The asker thanks the responder for their help.
  • #1
Femme_physics
Gold Member
2,550
1

Homework Statement



A truck drives in a straight line, east, from point A to point B, a distance of 180 meters, during 10 seconds, while slowing down at a constant rate of 6 meter per second squared.

Calculate the initial velocity.

The Attempt at a Solution



Attached. I don't think it's the correct answer, but according to the formula it should be!
 

Attachments

  • mechanicskinematics.jpg
    mechanicskinematics.jpg
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  • #2
Looks okay.
 
  • #3
Really? Because the solution manual tells me it's 21 m/sec. Did they make a mistake?
 

Attachments

  • theiranswer.JPG
    theiranswer.JPG
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  • #4
Who made the mistake depends upon whether the actual acceleration is 0.6m/s2 or 6m/s2. :smile:
 
  • #5
It's 0.6 m/s2, for sure.

So THEY'VE made the mistake, right? Can you officially confirm that THEY'VE made the mistake, and not me?
 
  • #6
Femme_physics said:
It's 0.6 m/s2, for sure.

So THEY'VE made the mistake, right? Can you officially confirm that THEY'VE made the mistake, and not me?

Officially, I'm here quite unofficially!:smile:

But in my opinion, if the problem statement say's that the acceleration is -6m/s2, then their solution is incorrect.
 
  • #7
No no, the problem statement says that acceleration is -0.6 m/s2. But, this is exactly what I plugged into the formula! So, now I'm confused, who's right here?
 
  • #8
Femme_physics said:
No no, the problem statement says that acceleration is -0.6 m/s2. But, this is exactly what I plugged into the formula! So, now I'm confused, who's right here?

Your problem statement was:

A truck drives in a straight line, east, from point A to point B, a distance of 180 meters, during 10 seconds, while slowing down at a constant rate of 6 meter per second squared.

and your solution image definitely shows a value of -6 being plugged in, the result for the (1/2)at2 term being given as 300m.
 
  • #9
Ahhhhhhhhhhhhhhh'I'm stupid. *smacky foreheady*

:) Thanks.<- Idiot. Seriously.

Appreciate it.

<- Seriously.

-FP
 

1. What is initial velocity in basic kinematics?

Initial velocity is the velocity of an object at the beginning of a motion or a specific point in time. It is denoted by the symbol 'u' and is measured in meters per second (m/s).

2. How is initial velocity calculated?

The formula for calculating initial velocity is u = (s/t), where u is the initial velocity, s is the displacement or distance traveled, and t is the time taken to travel. Alternatively, initial velocity can also be calculated using the formula u = v - at, where v is the final velocity, a is the acceleration, and t is the time taken.

3. Does initial velocity affect an object's motion?

Yes, initial velocity plays a crucial role in determining an object's motion. It determines the direction and speed of an object's motion and affects how the object will move over time.

4. How is initial velocity different from final velocity?

Initial velocity is the velocity of an object at the beginning of a motion, while final velocity is the velocity of the object at the end of the motion. Initial velocity is denoted by the symbol 'u', while final velocity is denoted by the symbol 'v'.

5. Can initial velocity be negative?

Yes, initial velocity can be negative. It simply indicates that the object is moving in the opposite direction of the positive direction that has been defined. For example, if a car is moving towards the west and the positive direction is towards the east, the initial velocity would be negative.

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