Solve Physics Q: Acceleration & Velocity of Object

In summary, the object initially has a velocity of 5.0 m/s and experiences an acceleration of 2.5 m/s2 from t=0 to t=5, and an acceleration of -0.1 m/s2 from t=5 to t=11. The average velocity of the object over the time interval t=5 to t=11 is 17.2 m/s. This is calculated by finding the total distance travelled by the object in that time interval and dividing it by the change in time.
  • #1
Kennedy
70
2
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An object, moving in a straight line, has a velocity of 5.0 m/s at time t = 0. From t = 0 to t = 5 s its acceleration is 2.5 m/s2 , while from t = 5 to t = 11 s its acceleration is - 0.1 m/s2 . Over the time interval t = 5 s to t = 11 s its average velocity is: (a) 15.0 m/s (b) 12.5 m/s (c) 17.2 m/s (d) 14.5 m/s (e) 8.8 m/s

I tried the question by finding the distance covered by the particle after the first time interval, then the second. I subtracted my first distance from the second to have the total distance traveled by the object between 5 and 11 seconds. Then, I divided by 6 for the change in time. My answer was 14.5 m/s, but apparently that's not the right answer. It should be 17.2 m/s according to my answer key, but I have no idea how they arrived at that answer. Can someone please work out the solution to this problem for me, please? I'm going based off of that the average velocity of an object is d/t
 
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  • #2
Your method is OK, but you must have made a mistake. Please show your calculations. At t=5s, the velocity is 17.5 m/s. At t=11s, it is 16.9 m/s. How could the average possibly be 14.5 m/s, smaller than both the velocity at the beginning and at the end?
 
  • #3
I had my distance covered in the first time interval to be 56.25 m (from 0 to 5), and my second distance to be 103.56 m (from 5 to 11, starting with an initial speed of 17.5 m/s). So, then the distance covered from 5 to 11 would be 103.56 m - 56.25 m, right? ...and then that answer divided by 6 (time interval)?
 
  • #4
Oh, I think I figured it out by talking it through. The answer should simply be 103.56/6... which yields 17.2 m/s! THANKS.
 

Related to Solve Physics Q: Acceleration & Velocity of Object

What is acceleration?

Acceleration is the rate of change of an object's velocity over time. It is a vector quantity, meaning it has both magnitude (how much the velocity changes) and direction.

What is the formula for acceleration?

The formula for acceleration is a = (vf - vi)/t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time. This is known as the average acceleration formula.

How is acceleration measured?

Acceleration is measured in units of meters per second squared (m/s²) in the SI system. In the English system, it is measured in feet per second squared (ft/s²).

What is the difference between acceleration and velocity?

Velocity is the rate of change of an object's position over time, while acceleration is the rate of change of an object's velocity over time. Velocity is a vector quantity, while acceleration is a vector quantity.

How does mass affect acceleration?

The greater the mass of an object, the more force is required to accelerate it. Therefore, objects with larger masses will have smaller accelerations compared to objects with smaller masses when the same force is applied.

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