# Can I find time without knowing initial velocity?

• Kearnsy101
In summary, the conversation discusses a problem involving displacement, acceleration, final velocity, coefficient of friction, and the weight of an object. The individual is unsure of how to find the initial velocity and time it took to slow down. They mention equations of motion and the relationship between frictional force and normal force. The conversation also suggests using work-energy relationships to solve the problem. Eventually, the individual has a breakthrough and concludes that the initial velocity is 14.7 m/s^2.
Kearnsy101
1. My problem is I know displacement is 20m, acceleration is -5.4m/s, final velocity is 0m/s, coefficient of friction=0.55, the object slowing down weighs 1000kg, can I find initial velocity and the time it took to slow down and if so how? I have no idea how to go about this problem
2. Equations of motion and coeffcient of friction = frictional force/normal force?? maybe F=ma
3. As I said I really don't know how to start this one or if its even possible at my level.

Do you have a formula that relates final velocity to initial velocity plus an acceleration-distance term?

You can also do this problem with work-energy relationships if you've studied that.

Hint:

Take the usual equation: d=V0*t+.5*a*t^2 and eliminate the variable t by inserting the relationship between final velocity, acceleration, and time. Solve for final velocity.

I woke up this morning, looked at this and it all just clicked in my head thankyou.

Is the initial velocity 14.7 m/s^2?

That's it.

## 1. What is the equation for finding time without knowing initial velocity?

The equation for finding time without knowing initial velocity is t = d/a, where t stands for time, d stands for distance, and a stands for acceleration.

## 2. Can I find time without knowing initial velocity if there is no acceleration?

Yes, if there is no acceleration, the equation for finding time without knowing initial velocity becomes t = d/v, where v stands for velocity. However, in order for this equation to work, the velocity must be constant.

## 3. Is it possible to find time without knowing initial velocity if there is both acceleration and deceleration?

Yes, it is possible to find time without knowing initial velocity if there is both acceleration and deceleration. In this case, you would need to use the average velocity, which is calculated by adding the initial velocity and final velocity and dividing by 2.

## 4. What if I only know the final velocity and not the initial velocity?

If you only know the final velocity and not the initial velocity, you can still find time by using the equation t = (v - u)/a, where v stands for final velocity, u stands for initial velocity, and a stands for acceleration. You would need to have the acceleration value in order to use this equation.

## 5. Are there any other ways to find time without knowing initial velocity?

Yes, there are other ways to find time without knowing initial velocity, such as using kinematic equations or using a motion graph. However, these methods may require additional information, such as the position or velocity at different points in time. Using the equations mentioned above is usually the simplest and most straightforward method.

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