gravity always applies downward force, so acceleration is down
depending on whether the tennis racket or foot is moving up or down, apply the appropriate force from that source.
What is the direction and sign of acceleration in each case.
A) stone was dropped from the top of a cliff. Neglect air drag.
b) tennis player hits a ball with a racket.
c) boy kicks in a soccer ball
2 answers
a. if z is up, g is down, negative
acceleration = -9.81 m/s^2 around here
b. If the player is looking toward the net, the force by the racket and resulting acceleration are positive.
c. again if x is forward the force of the foot on the ball and the acceleration are positive
HOWEVER - I think this question is questionable. If you define your directions opposite, your signs change.
acceleration = -9.81 m/s^2 around here
b. If the player is looking toward the net, the force by the racket and resulting acceleration are positive.
c. again if x is forward the force of the foot on the ball and the acceleration are positive
HOWEVER - I think this question is questionable. If you define your directions opposite, your signs change.
3 answers