Kinematics: acceleration and speed

In summary, the problem involves an automobile starting with a constant acceleration of 2.2 m/s^2 at the same time a truck overtakes and passes it with a constant speed of 9.5 m/s. The questions ask for the distance the automobile will overtake the truck and its speed at that instant. To solve, you can set up expressions for the position vs. time of both the car and the truck and set them equal at the instant of overtaking.
  • #1
mrsshakes
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Homework Statement



at the instant the traffic light turns green, an auto mobile starts with a constant acceleration of 2.2 m/s^2. At the same instant, a truck traveling with a constant speed of 9.5 m/s overtakes and passes the car.
a) how far beyond the traffic signal will the auto mobile overtake the truck?
b) how fast will the car be traveling at that instant?

Homework Equations



if I am only given the acceleration of the car and the velocity of the truck (the implied initial velocity is 0) how am i supposed to answer any of the questions?

The Attempt at a Solution


Given(car): a= 2.2 m/s^2, v1=0, d=?, t= ? given(truck): v= 9.5 m/s, v1= 0, d=?
 
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  • #2
Welcome to PF!

mrsshakes said:
if I am only given the acceleration of the car and the velocity of the truck (the implied initial velocity is 0)

No. Take t = 0 to be the instant at which the truck passes the car. Therefore, they both have the same starting position, and the initial velocity of the truck is 9.5 m/s.

mrsshakes said:
how am i supposed to answer any of the questions?

Write an expression for the position vs. time of the car.

Write another expression for the position vs. time of the truck.

At the instant the car overtakes the truck, their positions will be equal. What does this suggest that you should do with the two expressions?
 

1. What is acceleration?

Acceleration is the rate at which an object's velocity changes over time. It is a vector quantity, meaning it has both magnitude and direction. It is typically measured in meters per second squared (m/s²).

2. How is acceleration calculated?

Acceleration can be calculated by dividing the change in velocity by the change in time. 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.

3. What is the difference between positive and negative acceleration?

Positive acceleration is when an object's velocity is increasing, meaning its speed is getting faster. Negative acceleration, also known as deceleration or retardation, is when an object's velocity is decreasing, meaning its speed is getting slower.

4. How is speed related to acceleration?

Speed is the magnitude of an object's velocity, while acceleration is the rate of change of velocity. In other words, acceleration tells us how quickly an object's speed is changing. If an object has a constant speed, it has zero acceleration.

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

Average acceleration is the change in velocity over a specific time interval, while instantaneous acceleration is the change in velocity at a specific moment in time. Average acceleration can be calculated for any time interval, while instantaneous acceleration can only be calculated at a specific point in time.

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