Greetings everyone! I was wondering if someone could help me out
with a physics problem I saw in a book. I think I figured it out, but
I'm not sure if it's correct. Here's the question:
Imagine good ol' Grandpa Ester sitting in a frictionless wheeled chair,
with the inevitable wad of chewing tobacco lodged in his mouth. Assuming
he weighs 50Kg (including the wheel-chair), and is skilled enough in the
art of spitting to launch 1g of "projectile" at 5 m/s each time he spits,
how many "projectiles" would be needed to be launched to get him moving
at 1 m/s? Also, assume he periodically drinks some water to replace the
mass he is launching.
To solve it, I used a momentum formula: M1 x V1 = M2 x V2
M1 = mass of first object in Kilograms
V1 = Velocity of first object in meters per second
M2 = mass of second object in Kilograms
V2 = velocity of second object in meters per second
M1= 50Kg
V1 = ?
M2 = 1g = 0.001 Kg
V2= 5 m/s
Solving for V1 I get = 0.0001 m/s
Therefore, each time he spits, his velocity is increasing by 1x10^-4 m/s,
which means he would have to spit 10 000 times.
Is this correct? Any help would be greatly appreciated. If it is wrong,
could you please tell me where I went wrong?