A ball is thrown as a projectile with a horizontal velocity of 30 m/s and a vertical
velocity of 30 m/s. At the highest point which of the following is true?
A) The velocity is zero
B) The acceleration is 0
C) The acceleration is 9.8 m/s2
D) The acceleration is -9.8 m/s2
E) The vertical velocity is -30 m/s
To determine which statement is true at the highest point of the ball's trajectory, which is also the point of maximum height, we need to understand the motion of a projectile.
A projectile is an object that is launched into the air and moves under the influence of gravity. In this case, the ball is thrown horizontally with 30 m/s and vertically with 30 m/s.
At the highest point of a projectile's trajectory, its vertical velocity becomes zero. This is because the ball reaches its maximum height and momentarily stops moving upwards before starting to fall back down due to gravity. Therefore, option A) The velocity is zero is true at the highest point.
However, it's important to note that at the highest point, the ball still experiences acceleration due to gravity. Acceleration is the rate of change of velocity. In this case, the acceleration due to gravity is always acting vertically downward at approximately 9.8 m/s². So, option C) The acceleration is 9.8 m/s² is also true at the highest point.
To summarize, at the highest point of the ball's trajectory:
- The vertical velocity is zero (option A is true)
- The acceleration due to gravity is 9.8 m/s² (option C is true)