Calculate Time to Slow Down w/Static Friction on I-79 Exit 147A

[courtney1121]

A box full of fragile objects is on the back seat of your car. You are driving at 65 mph (29 m/s) on I-79. As you get off at exit 147A for Meadville, you must slow down to 0 mph. Estimate the minimum amount of time should you take to slow down (based on the appropriate acceleration) without the box sliding off the seat onto the floor on the car.

any thoughts on where to start?

we got acceleration due to gravity and velocity. We will have acceleration going in the opposite direction of motion.

 

[PhanthomJay]

A box full of fragile objects is on the back seat of your car. You are driving at 65 mph (29 m/s) on I-79. As you get off at exit 147A for Meadville, you must slow down to 0 mph. Estimate the minimum amount of time should you take to slow down (based on the appropriate acceleration) without the box sliding off the seat onto the floor on the car.

any thoughts on where to start?

we got acceleration due to gravity and velocity. We will have acceleration going in the opposite direction of motion.

You are missing some data. The problem cannot be solved unless you know the coefficient of static friction between the box and the seat. Was this info given? Otherwise, the time will have to be expresed as a function of the static friction coefficient. For starters, draw a FBD of the box and apply Newton's 2nd law.