Speed before impact of an object falling down a slope.

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SUMMARY

The discussion focuses on calculating the acceleration and velocity of a 4.7 kg block on a 14° incline, first without friction and then with a coefficient of kinetic friction of 0.25. The acceleration without friction is determined to be 2.36 m/s² using the formula FgSinθ/m. When considering friction, the force of friction (Ff) is calculated to be 11.18 N, leading to confusion regarding the block's movement, as the net force appears to be zero, suggesting no acceleration despite the block potentially having velocity.

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Homework Statement


A 4.7 kg block is placed on an incline with a 14° angle.
Ignoring friction, what is the acceleration of the block?
If the coefficient of kinetic friction is 0.25 (and has overcome static friction) what is the acceleration of the block?
If the incline is 4.6m long, what is the velocity of the block at the bottom (considering friction)?

Homework Equations


Ff=μFn
Fn=FgCosθ
Fg=4.7kg*9.81m/s^2
F=ma
Force on block due to gravity = 11.15N

The Attempt at a Solution


To find the first part, I used Fnet=ma, rearranged to find a and found the acceleration without friction to be:
FgSinθ/m = 46sin14°N/4.7kg = 2.36m/s^2

Then I calculated Ff to be 11.18N, which means there is no movement, and that is where I'm stumped because the last question would lead one to think that it moved somewhat.
 
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If the net force is zero, that means the acceleration is zero. It can still be moving (has velocity not zero).
 

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