Kinematics - Find acceleration

In summary, the conversation is about finding acceleration when given the distance a car stopped at and its initial speed of 80 km/h. The equations discussed are for constant acceleration and average velocity, and the one recommended for this problem is v^2=u^2 + 2as. The last part of the conversation is about whether the acceleration is constant or not, but since the question asks for acceleration, it is safe to assume that it is constant.
  • #1
888
13
0
hi,
i need help on a question... if a car stop in a distance of 50m from the speed of 80 km/h how do you find the acceleration is m/s/s? thanks
 
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  • #2
What equations of motion do you know? How about rearanging:

[tex] v^2=u^2 + 2as[/tex]
 
  • #3
i've never used that equation before but all the other equations i know are for constant acceleration or average velocity
 
  • #4
888 said:
i've never used that equation before but all the other equations i know are for constant acceleration or average velocity

Well what equations do you know?
 
  • #5
The equation I put up was for constant acceleration and speeds.
 
  • #6
the equations that i know are: aver. v= v2+v1/2
x2= x1+v1t+.5at^2
v^2=V1^2+2a(x2-x1)
v2= v1+at
those are only for constant acc.

aver acc= v2-v1/t2-t1
aver. vel.=x2-x1/t2-t1
 
  • #7
888 said:
v^2=V1^2+2a(x2-x1)

This is the same equation as Kurdt posted above, and it is the one that you should use to solve this problem.
 
  • #8
Thats just fine because you are looking for the constant acceleration.
 
  • #9
however the question doesn't say it's looking for constant acceleration
 
  • #10
888 said:
however the question doesn't say it's looking for constant acceleration

But it does say to find the acceleration, and unless you know how to find a non-constant acceleration you should just assume that you are looking for constant acceleration.
 

Related to Kinematics - Find acceleration

1. How do you calculate acceleration in kinematics?

In kinematics, acceleration is calculated by dividing the change in velocity by the change in time. This can be represented by the formula a = (vf - vi)/t, where vf is the final velocity, vi is the initial velocity, and t is the time interval.

2. What is the difference between average and instantaneous acceleration?

Average acceleration is the overall rate of change of velocity over a specific time interval, while instantaneous acceleration is the acceleration at a specific moment in time. In other words, average acceleration is the average of all the instantaneous accelerations during a certain time period.

3. How is acceleration related to velocity and displacement?

Acceleration is the rate of change of velocity, which means that it is directly related to velocity. If an object is accelerating, its velocity is changing. Displacement, on the other hand, is the change in position of an object over time. Acceleration affects displacement by changing the object's velocity, which then changes its position.

4. Can an object have a constant velocity and still have acceleration?

No, an object cannot have a constant velocity and still have acceleration. Acceleration is defined as a change in velocity, so if an object's velocity is constant, there is no change and therefore no acceleration.

5. How does mass affect acceleration?

According to Newton's Second Law of Motion, the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass. This means that as mass increases, acceleration decreases, and vice versa. For example, a heavier object will require more force to accelerate it at the same rate as a lighter object.

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