Aim: How do we use Newton’s equation of Motion to explain the motion of a free falling projectile?

Free Fall All bodies accelerate downwards at -10m/s2 on earth regardless of mass (in the absence of air resistance). On the moon, the acceleration due to gravity is -1.62 m/s2 . Since there is no air resistance on the moon, a penny and feather will hit the ground at the same time.

Free Fall Problem How long does it take for a basketball to hit the ground when dropped off of the Empire State Building which is 381 meter? 8.82s With what speed does the ball hit the ground? 88.2 m/s

Projectiles Fired Upwards We know three things about projectiles thrown upwards: (Assume no air resistance) The velocity of the projectile at its maximum height is equal to 0.

Projectiles Fired Upwards 2. The time it takes the object to rise is equal to the time it takes the object to fall the same amount of distance.

Projectiles Fired Upwards 3. The velocity with which the projectile is launched upwards will be equal in magnitude to the velocity of the projectile when it hits the ground.

Projectiles Fired Upwards Note: When solving projectile motion problems in which the projectile is fired upwards, it is especially important that we make acceleration vector negative (-9.8) and the initial velocity vector is positive.

Problem A Gwendolyn throws her crystal vase vertically upwards with an initial velocity of 26.2 m/s. Determine how long the crystal vase is in the air if Gwendolyn is 1.2 m tall. Solve for time it takes to reach max height. Solve for distance it rises. Solve for time it takes to fall. Answer: t=5.29 s

Problem B-Firing a projectile downwards A mischievous child shoots a pellet out of a BB gun downwards with a velocity of 20 m/s from the top of a building which is 45 m tall. How long does it take the pellet to hit the ground? Vi= -20 m/s Y= -45 m A= -10 m/s^2 Use y=vit +1/2at^2 t= 1.6s