Question

A person holds a portable fire extinguisher that ejects 1.0kg of water per second horizontally at a speed of 6.0 m/s. What newtons must the person exert on the extinguisher in order to prevent it from accelerating?
(A) 0N
(B) 6N
(C) I0N
(D) 18N
(E) 36N

Answer 1

Answer:

6 N

Explanation:

$\dfrac{m}{t}$ = Mass flow rate = 1 kg/s

v = Final velocity = 6 m/s

u = Initial velocity = 0 m/s

Force is obtained when we divide change in momentum by time

$F=\dfrac{m(v-u)}{t}\\\Rightarrow F=\dfrac{m}{t}(v-u)\\\Rightarrow F=1(6-0)\\\Rightarrow F=6\ N$

The force the person exert on the extinguisher in order to prevent it from accelerating is 6 N