Speed before impact of an object falling down a slope.

Click For 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 initial acceleration without friction is determined to be 2.36 m/s². When considering friction, the force of friction calculated is 11.18 N, leading to confusion about the block's movement since the net force appears to be zero. The key takeaway is that while the net force can be zero, the block can still have a non-zero velocity due to its initial motion. Understanding the distinction between acceleration and velocity is essential in this context.
DAN393
Messages
2
Reaction score
0

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.
 
Physics news on Phys.org
If the net force is zero, that means the acceleration is zero. It can still be moving (has velocity not zero).
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 9 ·
Replies
9
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 19 ·
Replies
19
Views
4K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 12 ·
Replies
12
Views
6K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 3 ·
Replies
3
Views
12K