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Speed = distance/time

  • Thread starter jkt
  • Start date

jkt

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1. Homework Statement

I'm trying to solve the following problem to help my son with his homework....

Suppose you build a motor car that travels across a table top a distance of 1.5 meters in 1.2 seconds. The table is 0.8 m tall. The mass of the car is 300 grams. Ignore friction, air resistance.
1) If we assume that its acceleration is uniform, what is the acceleration of the car while rolling on the table? The correct answer is 2.1 m/s/s....but i don't understand how that answer was arrived at.

2) What would be the velocity of the car after it has accelerated across the table top for the distance of 1 meter? The correct answer 2.5 m/s...but once again, I don't understand it. Any help for the weary mom?


2. Homework Equations

speed = distance/time


3. The Attempt at a Solution


1.5/1.2
 
Last edited by a moderator:
2,036
2
speed = distance/time
That would apply if the speed was same during the travel. speed/time, in this problem, would only result in the average speed.

Given distance and time, which of the kinematic equations would you use to find the acceleration?

(I guess the you've to assume that the car starts from rest)
 

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