Calculating deacceleration force

[Valarg]

Homework Statement

An object is moving at a velocity of 28m/s
The mass is 100kg
It deaccelerates from 28m/s to 0 in a distance of 5m

How much force (N) is needed to stop the object?

Homework Equations

The Attempt at a Solution

I need help, please! :)

 

[PhanthomJay]

You can use one of the kinematic eqations of motion to solve for the deceleration; and then use one of Newton's law to solve for the force. Or use energy methods. Please show what you have tried or your attempt at a solution.

 

[Valarg]

Currently I got a 39,4C fever and have problems concentrating.

I understand that I probably need to use the f=ma basic formula but what I can't get my head around is the conversion to time.

Meaning I have the velocity, mass, deacceleration distance, and changes in velocity, still, I can't get my sore head to comprehend how to extract time from it, I´m stuck so unfortunatley I have no formula or attempt to a solution.

 

[PhanthomJay]

Currently I got a 39,4C fever and have problems concentrating.

I understand that I probably need to use the f=ma basic formula but what I can't get my head around is the conversion to time.

Meaning I have the velocity, mass, deacceleration distance, and changes in velocity, still, I can't get my sore head to comprehend how to extract time from it, I´m stuck so unfortunatley I have no formula or attempt to a solution.

Yow, you can't do too much with a 103 (degrees F) temp! Get well soon!

You don't need time; there is a basic kinematic equation that relates velocity with acceleration and distance. For a final velocity of 0, does v^2 = 2(a)(s) sound familiar, where v = 28, and s =5, then solve for a. Take care.

 

[Valarg]

You are right, I really should leave this for tomorrow instead!

Thanx a bunch for your help! looks like it solved my problem! :)

 

[PhanthomJay]

You are right, I really should leave this for tomorrow instead!

Thanx a bunch for your help! looks like it solved my problem! :)

I might have given you a bit too much help, but while still working with a 39,4, you deserved it.