Responding to an alarm, a 80 kg fireman slides down a pole to the ground floor, 3.2 m below. The fireman starts at rest and lands with a speed of 3.7 m/s.
(a) Find the average force exerted on the fireman by the pole.
Answer in N
(b) If the landing speed is half that in part (a), is the average force exerted on the fireman doubled?
yes or no ?
(c) Find the average force exerted on the fireman when the landing speed is 1.85 m/s.
Answer in N
Can some help?
(a) Find the average force exerted on the fireman by the pole.
Answer in N
(b) If the landing speed is half that in part (a), is the average force exerted on the fireman doubled?
yes or no ?
(c) Find the average force exerted on the fireman when the landing speed is 1.85 m/s.
Answer in N
Can some help?
-
Acceleration due to gravity = 9.81 m/s^2
Force on fireman due to gravity
= 80 * 9.81 = 784.8 N
a)
v^2 = u^2 + 2as
3.7^2 = 0^2 + 2a*3.2
a = 3.7^2 / (2 * 3.2) = 2.1390625 m/s^2
Net force accelerating fireman down the pole
= 2.1390625 * 80 = 171.125 N
Average force exerted by the pole on the fireman
= 784.8 - 171.125 = 613.675 N
b)
NO
c)
1.85^2 = 2a*3.2
a = 1.85^2 / (2 * 3.2)
= 0.534765625 m/s^2
Net force accelerating the fireman down the pole
= 0.534765625 * 80 = 48.78125 N
Average force exerted on fireman by the pole
= 784.8 - 48.78125 = 742.01875 N
Force on fireman due to gravity
= 80 * 9.81 = 784.8 N
a)
v^2 = u^2 + 2as
3.7^2 = 0^2 + 2a*3.2
a = 3.7^2 / (2 * 3.2) = 2.1390625 m/s^2
Net force accelerating fireman down the pole
= 2.1390625 * 80 = 171.125 N
Average force exerted by the pole on the fireman
= 784.8 - 171.125 = 613.675 N
b)
NO
c)
1.85^2 = 2a*3.2
a = 1.85^2 / (2 * 3.2)
= 0.534765625 m/s^2
Net force accelerating the fireman down the pole
= 0.534765625 * 80 = 48.78125 N
Average force exerted on fireman by the pole
= 784.8 - 48.78125 = 742.01875 N