Physics Unit 3 Falling Bodies

Which of the following quantities is a vector which changes signs (directions) when an object that was thrown upward stops rising and begins to fall?

velocity

A ball is dropped (near the earth). How fast is it moving at the end of its first second of free-fall?

9.80 m/s

Which pair of graphs show the free-fall velocity and acceleration of an object which is dropped from rest?

F

When an object that was thrown upward reaches its highest point, which statement is true?

The velocity is zero

A ton of feathers and a ton of bricks are dropped from the same height on the moon. What happens?

The feathers and bricks strike the ground simultaneously

A stone is thrown upward from atop a cliff and then lands at the base of the cliff. Which statement is true if the upward direction is considered "positive" ?

The final displacement of the stone is negative

According to Aristotle, a man weighing 150 pounds would fall to Earth how much faster than a boy weighing 50 pounds?

3 times as fast

Part c) How long after it leaves the hand will it return to the starting point?

3.57 s + 3.57 s = 7.14 s

How far has the ball in the previous question displaced at the end of its first second of free-fall?

4.90 m/s

Which pair of graphs show the free-fall displacement and velocity of an object which is thrown upward and later caught at its original height?

B

Which pair of graphs show the free-fall velocity and acceleration of an object which is thrown upward and later caught at its original height?

D

Which pair of graphs show the free-fall displacement and velocity of an object which is dropped from rest?

E

Part b) How high will it rise?

Given a = -9.80 m/s^2 vi = 35.0 m/s t = 3.57 s vf = 0 x = ? formula -> x = (vi+vf)t/2 (35+0)3.57/2 x = 31.2 m

A baseball is thrown upward with a speed of 35.0 m/s. Part a) How long will it rise?

Given a = -9.80 m/s^2 vi = 35.0 m/s vf = 0 t = ? formula -> t = vf-vi/a 0-35/-9.80 t = 3.57. s

Part b) How far above the bottom was the nut 0.154 s after it fell off?

Given t = .154 s a = -9.80 m/s^2 vi = 4.00 m/s x = ? formula -> x = vi(t)+(1/2)a(t)^2 4(.154)+(1/2)(-9.8)(.154)^2 x = 0.50 m 0.50-(-11.6) = 12.1 m

If the student decided to throw an egg downward, and it struck Mr. M after 1.3 s, what was the initial velocity of the egg?

Given t = 1.3 s vi = ? a = -9.8 m/s^2 d = -19.6 m formula -> d = vi(t)+(1/2)a(t)^2 -19.6 = (1.3)+(1/2)(-9.8)(1.3)^2 -19.6 = 1.3vi+7.056 vi = -22.2 m/s

A nut comes loose from a bolt on the bottom of an elevator as the elevator is moving up the shaft at 4.00 m/s. The nut strikes the bottom of the shaft in 2.00 s. Part a) How far from the bottom of the shaft was the elevator when the nut fell off?

Given t = 2.00 s a = -9.80 m/s^2 vi = 4.00 m/s vf = ? x = ? formula -> x = vi(t)+(1/2)a(t)^2 4(2)+(1/2)(-9.8)(2)^2 x = 11.6 m downward

A bottle is dropped from a balloon reaches the ground in 7.00 s. Part a) Determine the height of the balloon when the bottle was released if the balloon was at rest in the air when the bottle was dropped.

Given t = 7.00 s a = -9.80 m/s^2 vf = 0 x = ? formula -> x = vi(t)+(1/2)a(t)^2 (1/2)(-9.8)(7)^2 x = -240.1 m

Part b) Determine the height of the balloon when the bottle was released if the balloon had been rising at a speed of 2.00 m/s when the bottle was released, and the bottle still took 7.00 s to reach the ground.

Given vi = 2 m/s a = -9.80 m/s^2 t = 7.00 s x = ? formula -> x = vi(t)+(1/2)a(t)^2 2(7)+(1/2)(-9.8)(7)^2 x = -226.1 m d = vt 2(7) = 14 .. = -212.1

A stone is shot straight upward with a speed of 25.5 m/s from a tower and lands at the base of the tower with a speed of 35.0 m/s. How long does it take?

Given vi = 25.5 m/s vf = 35.0 m/s a = -9.80 m/s^2 t = ? formula -> t = vf-vi/a -35.0 - 25.5/-9.80 t = 6.17 s

Part d) When will its speed be 16.5 m/s? (two parts)

Given vi = 30 m/s vf = 16.5 m/s a = -9.80 m/s^2 t = ? formula -> t = vf-vi/a 16.5-30/-9.8 1.38 s -16.5-30/-9.8 = -9.8 s

An angry Physics student decides to throw an egg onto the head of poor Mr. M. The student leans out of a school window 17.6 m above the head of the head of the approaching instructor. Part a) Determine how many seconds before the teacher is directly under him that he will have to drop the egg in order to get the desired splat.

Given x = 17.6 m a = -9.8 m/s^2 vi = 0 t = ? formula -> d = vi(t)+(1/2)a(t)^2 17.6 = (1/2)(-9.8)t^2 17.6/4.95 = 4.95t^2/4.95 t^2 = 3.96 t = 1.99 s

Galileo's Discourses on Two New Sciences contradicted that assertion. It was a conversation between...

three characters with each representing a different viewpoint