You are sitting on a bus moving at 50 km/h [E]
when you toss a ball in front of you and straight up
into the air. The ball reaches a height close to your
eyes. Will the ball hit you in the face? Explain.
no
the bus is an "inertial reference frame"
the ball is moving , along with you , in the bus
tossing the ball perpendicular to the direction of motion of the bus
... doesn't change the ball's horizontal motion
No, the ball will not hit you in the face. This is because as the bus moves forward, you and the ball are also moving forward with the same velocity. When you toss the ball straight up in the air, it will have the same horizontal velocity as the bus. So, even though the ball goes straight up and comes back down, it will still have the same horizontal velocity as the bus. Consequently, the ball will land back in your hand, rather than hitting you in the face.
To determine whether the ball will hit you in the face, we need to consider two factors: the horizontal velocity of the ball relative to the bus and the vertical velocity of the ball.
Let's break it down step by step:
1. Horizontal Velocity: The ball is thrown in front of you, but since you and the ball are on the same moving bus, the ball also inherits the bus's velocity. This means that the ball has the same horizontal velocity as the bus, which is 50 km/h to the east.
2. Vertical Velocity: When you toss the ball upwards, it will initially have an upward velocity due to the force exerted on it. However, after being released, the only force acting on the ball is gravity, which pulls it downwards. This results in the ball's vertical velocity decreasing over time.
Now, let's consider what happens when you throw the ball:
Since the ball initially has an upward velocity and the bus keeps moving east at a constant speed, the downward pull of gravity will eventually overpower the upward velocity of the ball. As a result, the ball will start to fall downwards.
Although the ball and the bus are both moving forward at the same speed, the downward force of gravity acting on the ball will cause it to fall behind the bus. Therefore, the ball will ultimately miss your face and fall behind you, assuming you continue to move with the bus and do not lean forward.
In summary, the combination of the ball's initial upward velocity and the downward force of gravity will cause the ball to miss your face as it falls behind you while you are both on the moving bus.