# Problems with calculating the acceleration

• PhyIsOhSoHard
In summary, the block moves a distance of 11 meters in 5 seconds on a straight line. To calculate the acceleration, we can use the equation a_x = (v_x)^2 / 2x, which gives us three different answers due to the different values of Vx (instantaneous velocity) and V0x (initial velocity). However, since the block starts at rest (V0x = 0), the correct equation to use is a_x = 11m / (1/2(5s)^2), which gives an acceleration of 0.88m/s^2.
PhyIsOhSoHard

## Homework Statement

A block moves 11 meters in 5 seconds on a straight line. Calculate the acceleration.

## Homework Equations

$v^2_x=v^2_{0x}+2a_x(x-x_0)$

$v_x=v_{0x}+a_xt$

$x=x_{0}+v_{0x}t+\frac{1}{2}a_{x}t^2$

## The Attempt at a Solution

$a_x=\frac{(\frac{11m}{5s})^2}{2\cdot 11m}=0.22m/s^2$

$a_x=\frac{(\frac{11m}{5s})}{5s}=0.44m/s^2$

$a_x=\frac{11m}{1/2\cdot (5s)^2}=0.88m/s^2$

Why am I getting 3 different answers? In my textbook, it lists the equations as being practically the same (straight-line motion with constant acceleration).

Assuming V0x = 0, then Vx ≠ 11/5 m/s.

1 person
lewando said:
Assuming V0x = 0, then Vx ≠ 11/5 m/s.

yes, V0x=0 because it starts at rest. But how do you know the velocity is not 11/5 m/s then?

11/5 m/s is the average velocity. Vx is the instantaneous velocity at the 5m point.

1 person
lewando said:
11/5 m/s is the average velocity. Vx is the instantaneous velocity at the 5m point.

Ohhhh.
And because of that, I cannot use any of the formulas which includes the Vx therefore the only correct equation for my current problem is the 3rd, correct?

Yes!

1 person

## What is acceleration and why is it important?

Acceleration is the rate of change of velocity over time. It is important because it allows us to understand how quickly an object's velocity changes and how fast it is moving.

## What are some common problems with calculating acceleration?

Some common problems with calculating acceleration include not having accurate measurements of velocity and time, not taking into account external forces such as friction or air resistance, and not using the correct formula to calculate acceleration.

## How do I calculate acceleration?

Acceleration can be calculated by dividing the change in velocity by the change in time. The formula for acceleration is a = Δv/Δt, where a is acceleration, Δv is change in velocity, and Δt is change in time.

## What are the units for acceleration?

The units for acceleration are meters per second squared (m/s²) in the metric system and feet per second squared (ft/s²) in the imperial system.

## How does acceleration relate to other concepts in physics?

Acceleration is closely related to other concepts in physics such as velocity, displacement, and force. It is a key component in understanding the laws of motion and how objects move in the physical world.

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