Final answer:
The question from a student involves calculating the velocity of a ball after 3 seconds and the displacement between the 3rd and 4th seconds of its flight, applying principles of projectile motion in physics. So, the best answer is a) Velocity within 3 seconds and displacement between the 3rd and 4th second
Step-by-step explanation:
Understanding Projectile Motion
A student asked what would be the velocity of a ball within 3 seconds of being thrown from a rooftop with an initial velocity of 5 m/s, and what the displacement would be between the 3rd and 4th second of its flight.
To solve this, we use the principles of projectile motion, which is part of classical mechanics in physics.
When calculating these values, we assume a consistent acceleration due to gravity (approximately 9.81 m/s2 downward) and neglect air resistance.
The velocity after 3 seconds depends on the direction of the initial throw.
If it were thrown purely vertically upward, for example, you would subtract the product of the acceleration due to gravity and time (9.81 m/s2 * 3 s) from the initial velocity.
Displacement between the 3rd and 4th seconds would involve calculating the distance the ball travels during the 3rd second, then the distance during the 4th second, and finding the difference between the two.
This kind of question applies the kinematic equations for uniformly accelerated motion.
So, the best answer is a) Velocity within 3 seconds and displacement between the 3rd and 4th second