What is the required force to pull a shopping car?
JerichoX asked:
A woman pulls a shopping car with a force F at an angle of 35. The car mass is 20kg and its friction coefficient is 0.05. Find:
(A) The force the woman needs to apply to move the car with a constant velocity of 1m/s.
(B) The magnitude of the normal force and friction when the car moves at constant velocity.
(C) The force the woman needs to exert to push the car with a constant velocity of 1/s.
(D) The Displacement if the car is pushed 5 seconds and the displacement if the car is pulled 5 seconds.
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A woman pulls a shopping car with a force F at an angle of 35. The car mass is 20kg and its friction coefficient is 0.05. Find:
(A) The force the woman needs to apply to move the car with a constant velocity of 1m/s.
(B) The magnitude of the normal force and friction when the car moves at constant velocity.
(C) The force the woman needs to exert to push the car with a constant velocity of 1/s.
(D) The Displacement if the car is pushed 5 seconds and the displacement if the car is pulled 5 seconds.
October 31st, 2009 at 12:17 pm
The formula for friction is
Fr = μR
Where μ is the coefficient of friction, and
R is the normal contact force.
So the normal contact force will be
Mass x gravity = 50*9.81 = 490.5
0.37 * 490.5 = 181.485 N
It is worth noting that that answere is too precise and also that I ignored the vectors and just used magnitude, in more difficult problems you will need to use vectors. Itzel
November 1st, 2009 at 12:02 pm
……..Fy………F
…W…↑…….⁄
….↓….|….⁄_35°
._▓▓._|.⁄——→Fx
╘O=O╛←――Ff
▒▒↑▒▒▒▒▒▒▒▒▒▒▒▒
…..|
….N.
Given:
W = mg = 20kg(9.8)
µ = 0.05
(A) Force needed to PULL the car at a constant speed.
‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Summation of forces along the Y-axis = 0
∑Fy = 0
0 = -W + N + Fy
…= -mg + N + Fsin35°
N = mg - Fsin35° ………..◄eq1
Summation of forces along the X-axis = 0
∑Fx = 0
0 = Fx - Ff
Ff = Fx
Ff = Fcos35°
But Ff = µN … Questor
November 4th, 2009 at 4:42 am
for the diagram—
[only ten people can dwnld]
[some one please re-upload it after reading the answer]
this is the hint
if u are able to solve it then exellent.
if not please ask again. Matt