Question

A 54.8-kg baseball pitching machine is placed on a frozen pond. It fires a 0.133-kg baseball at an angle of 30 degrees with the vertical at a speed of 18.5 m/s. What is the recoil velocity (in cm/s) of the machine?

Answer 1

Answer on Question #39107, Physics, Mechanics

Question:

A 54.8-kg baseball pitching machine is placed on a frozen pond. It fires a 0.133-kg baseball at an angle of 30 degrees with the vertical at a speed of 18.5 m/s. What is the recoil velocity (in cm/s) of the machine?

Answer:

The law of conservation of momentum:

$$m v _ {x} = M u$$

where $m$ is baseball's mass, $M$ mass of pitching machine, $u$ is the recoil velocity:

$$v _ {x} = v \sin 3 0 = \frac {v}{2}$$

Therefore the recoil velocity equals:

$$u = \frac {m v _ {x}}{M} = \frac {0 . 1 3 3 * 1 8 . 5}{2 * 5 4 . 8} = 2 2. 4 \frac {c m}{s}$$

Answer: $22.4\frac{cm}{s}$