# Need find end velocity given accel., time, distance

• LVanderlinden
In summary, the driver of a car experiences a constant acceleration of -5.90 m/s2 when braking to avoid a tree. The car travels 60.0 m in 4.45 s before coming to a stop at the tree. To find the speed at which the car strikes the tree, the equation x = x0 + v0t + 1/2at^2 is used. However, the equation used to find v0 is incorrect.

#### LVanderlinden

urgent! Need find end velocity given accel., time, distance

1.The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows with a constant acceleration -5.90 m/s2 for 4.45 s, making straight skid marks 60.0 m long ending at the tree. With what speed does the car then strike the tree?

## The Attempt at a Solution

so I tried to find Vo using Vo=x-at^2/2
and I plugged Vo into Vf=Vi+at and got 13.4 but it was wrong.
Please help me I am so confused.

LVanderlinden said:
1.The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows with a constant acceleration -5.90 m/s2 for 4.45 s, making straight skid marks 60.0 m long ending at the tree. With what speed does the car then strike the tree?

## The Attempt at a Solution

so I tried to find Vo using Vo=x-at^2/2
and I plugged Vo into Vf=Vi+at and got 13.4 but it was wrong.
Please help me I am so confused.

The equation in red is wrong. See again the equation of motion (for position vs time).
The idea of using the two equations to eliminate vo is OK.

## 1. How do I find the end velocity when given acceleration, time, and distance?

To find the end velocity, you can use the formula: vf = vi + at, where vf is the final velocity, vi is the initial velocity, a is the acceleration, and t is the time. You will also need to use the formula: d = vit + (1/2)at^2, where d is the distance. Plug in the known values and solve for vf.

## 2. Can I use this formula for any type of motion?

Yes, this formula can be used for any type of motion as long as the acceleration is constant. If the acceleration is not constant, you will need to use more advanced equations, such as the calculus-based equations of motion.

## 3. What units should I use for acceleration, time, and distance?

Acceleration is typically measured in meters per second squared (m/s^2), time is measured in seconds (s), and distance is measured in meters (m). It is important to make sure all units are consistent in order to get an accurate result.

## 4. What do I do if I am missing one of the values in the equation?

If you are missing one of the values, you can rearrange the formula to solve for the missing variable. For example, if you are missing the final velocity, you can rearrange the formula vf = vi + at to solve for vf.

## 5. Is there a faster way to calculate the end velocity?

Yes, there is a shortcut formula for finding the end velocity when given acceleration, initial velocity, and distance. The formula is: vf^2 = vi^2 + 2ad. This formula can save time and steps when solving for the end velocity.