A boy throws the ball vertically upwards with an initial velocity of 15m\s,what is the magnitude and direction of the ball
Magnitude of what? The velocity? That would be 15 m/s and the direction would be "up".
To determine the magnitude and direction of the ball, we can analyze the motion of the ball when it is thrown vertically upwards.
1. Magnitude of the ball's velocity:
The initial velocity of the ball is given as 15 m/s in the upward direction. However, due to the effect of gravity, the ball's velocity decreases until it reaches its maximum height. At the highest point, the velocity is reduced to zero. The magnitude of the ball's velocity remains constant throughout its motion, which is initially 15 m/s.
2. Direction of the ball's velocity:
The ball is thrown upwards, so its initial velocity is in the upward direction. As gravity acts in the downward direction, the direction of the ball's velocity changes from upward to downward as it reaches the highest point and starts coming back down. At the peak of its trajectory, the velocity is momentarily zero, and as the ball descends, the velocity becomes negative (directed downward). Thus, the direction of the ball's velocity changes from upward to downward as it moves.
In summary, the magnitude of the ball's velocity remains constant at 15 m/s, and the direction of the velocity changes from upward to downward as the ball moves.