Answer:
The upward force F was 546.11 N
Explanation:
In order to find the value of the force F, you have to apply Newton's Second Law:
∑F=ma
where F represents all the forces, m is the mass and a is the acceleration.
In this case, the applied forces are the force F exerted by the pole and the weight force, due to the acceleration of gravity.
Replacing in the formula the components of the forces in the y-axis:
Using a positive direction downward:
-F + W = ma
-F + mg=ma
F = mg - ma (I)
Notice that F is upward and the weight is downward.
You need to calculate the acceleration with the given information and then you can calculate the value of F.
Applying kinematic motion formula:
Yf= Yo+ Vot + 0.5at²
where yo is the initial position, vo is the initial velocity, a is the acceleration, t is the time and Yf is the final position.
In this case:
t=1.2s
vo=0 (because the fireman starts from rest)
Yo= 0 m and Yf= 3.0 m
Therefore:
3.0 = 0 + 0(1.2) + 0.5a(1.2)²
3.0 = 0.72a
Dividing by 0.72
a = 4.17 m/s²
Replacing it in (I):
F= 97(9.8) - 97(4.17)
F = 546.11 N
