Back again, Another question about friction

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To determine the frictional force acting on a skater slowing down from 10.0 m/s to 4.0 m/s over 2.0 seconds, first calculate the skater's acceleration using the formula for constant acceleration. The acceleration can be found by taking the change in velocity divided by the time interval, resulting in a negative value since the skater is decelerating. Once the acceleration is established, apply Newton's second law, which states that the net force equals mass times acceleration, to find the frictional force. The skater's mass is 70 kg, and this value will be used in conjunction with the calculated acceleration to derive the magnitude of the frictional force. Understanding these relationships will clarify how to approach the problem effectively.
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Hey again, once again I have no idea where to start on an equation that I received on a quiz

A 70 kg skater initially moving at 10.0 m/s across the ice drags the rough part of one skate along the ice, slowing herself to 4.0 m/s over a 2.0 s period of time. What is the magnitude (a positive number) of the frictional force on her during the time she is slowing down? [Assume her acceleration is constant.]

I did some models with force diagrams and such on my own, but once again I couldn't really figure out anything from them. If someone could once again point me in the right direction generally on how to go about this I would be extremely greatful. Thank you in advance.
 
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1.How can the acceleration be written in terms of the frictional force and the skaters mass?
2. since the acceleration is constant, how does the velocity of the skater vary with time?
 
Try to calculate the acceleration of the skater from the given initial and final velocities for the 2.0 s interval using your constant acceleration equations. One you've got that the frictional force can be calculated from Newton's second law, since it is this force that caused that particular acceleration.
 
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