- #1
hairE
- 1
- 0
p
A 5.03 box sits at rest at the bottom of a ramp that is 8.76 long and that is inclined at 30.0 above the horizontal. The coefficient of kinetic friction is 0.40, and the coefficient of static friction is 0.50.
What constant force , applied parallel to the surface of the ramp, is required to push the box to the top of the ramp in a time of 4.45 ?
max mu_static * force Normal = Force to budge Block
mu_kinetic * force Normal = Force Friction
The force to overcome the static friction is what is confusing me.
To start: Find acceleration.
8.76m / 4.45 s = 1.969 m/s = veloc.
1.969 m/s /4.45 s = .4425 m/s^2 = accel.
F= ma = 5.03*.4425 = 2.225 N = Leftover, or net force to keep the block accelerating up the ramp
(Parallel to plane) ƩF= Push - Force static - force kinetic - Weight = 2.25N
2.25N = Push - mgsin(30) - (mu_k)mgcos(30) - (mu_s)mgcos(30)
BUT*** Force static is only acting until the object budges. And the question is asking for a CONSTANT force applied. I'm confused. PLEASE help! I just need the sum of forces explained to me.
Homework Statement
A 5.03 box sits at rest at the bottom of a ramp that is 8.76 long and that is inclined at 30.0 above the horizontal. The coefficient of kinetic friction is 0.40, and the coefficient of static friction is 0.50.
What constant force , applied parallel to the surface of the ramp, is required to push the box to the top of the ramp in a time of 4.45 ?
Homework Equations
max mu_static * force Normal = Force to budge Block
mu_kinetic * force Normal = Force Friction
The Attempt at a Solution
The force to overcome the static friction is what is confusing me.
To start: Find acceleration.
8.76m / 4.45 s = 1.969 m/s = veloc.
1.969 m/s /4.45 s = .4425 m/s^2 = accel.
F= ma = 5.03*.4425 = 2.225 N = Leftover, or net force to keep the block accelerating up the ramp
(Parallel to plane) ƩF= Push - Force static - force kinetic - Weight = 2.25N
2.25N = Push - mgsin(30) - (mu_k)mgcos(30) - (mu_s)mgcos(30)
BUT*** Force static is only acting until the object budges. And the question is asking for a CONSTANT force applied. I'm confused. PLEASE help! I just need the sum of forces explained to me.