A baseball player uses a pitching machine to help him improve his batting average. he places the 54.6 kg machine on a frozen pon
d. the machine fires a 0.149 kg baseball horizontally at a speed of 42.6 m/s. what is the magnitude of the recoil velocity of the machine? answer in units of m/s.
When the object is moving in one plane, the velocity, acceleration, and displacement are vectors. Apart from the magnitudes, we also need to find the direction, often expressed as an angle respect to some reference.
Our boy can swim at 3 m/s from west to east in still water and the river he's attempting to cross interacts with him at 2 m/s southwards. The boy will move east and south and will reach the other shore at a certain distance to the south from where he started. It happens because there is a vertical component of his velocity that is not compensated.
To compensate for the vertical component of the boy's speed, he only has to swim at a certain angle east of the north (respect to the shoreline). The goal is to make the boy's y component of his velocity equal to the velocity of the river. The vertical component of the boy's velocity is
where is the speed of the boy in still water and is the angle respect to the shoreline. If the river flows at speed , we now set