Posted by Alex on .
A block of mass 0.5 kg rests on a smooth inclined plane. It is then pushed by a horizontal force of 16N. When the block has displaced 5m along the inclined plane.
What would be the speed of the block if the plane is rough and a friction of 5N is acting on the block?
Q. incomplete and/or not clear -
It is not clear to me
1. how a block will "rest" on a smooth inclined plane, and
2. in which direction is the horizontal force acting, towards up the plane, or down?
3. The first paragraph seems incomplete
I don't know.....it's written like that in the book...... It's being pushed up....... the answer is 12.9m/s.....But I dun know how to calculate it......
Do you have a diagram that shows the angle of the incline and the direction of the force?
no....sorry I forgot to mention, the angle is 20 degree.....
Resolve forces along the inclined plane of inclination θ=20°:
For the mass, m = 0.5 kg
and the applied force, F = 16N
component of force down the incline,
Fm = mg*sin(θ)
Due to force F, component up the incline,
Ff = Fcos(θ)
Net force up,
Acceleration up the plane
a = F/m
Initially at rest, u=0, and final velocity v after travelling a distance of S = 5m,
use the relation
v²-u² = 2aS
Solve for v in m/s. I get 12.9 m/s.
But I get 17.9m/s..... acceleration is equal to net force over mass or just force over mass?
Anything wrong with my steps?
Can I minus 17.9 by 5N which is the friction?
I get it now......Thanks alot.....