I am trying to study for an exam, but I got some practice questions wrong that I'd like to understand to study better. Can someone help me? Thanks!(adsbygoogle = window.adsbygoogle || []).push({});

(I don't just want the answer please, I really want to understand this stuff. If you have time, please explain? I'd like to check myself and figure it out.)

1. Two balls ( red and blue) released at the same time from the same height above ground. Which ball has the highest final speed?

<img src="http://img103.imageshack.us/img103/1997/2ballsmg3.gif"> [Broken]

My answer: both balls hit the ground at the same speed

choices:

a. The blue ball

b. The red ball

c. Both balls hit the ground at the same time

d. More information is needed to answer the question

2. The figure below shows 2 balls ( red and blue) released at the same time from the same height above ground. Which ball has the highest initial velocity?

(same graph as #1)

My answer: both balls have the same initial velocity

choices:

a. The blue ball

b. The red ball

c. The initial velocity is the same for both balls

d. More information is needed to answer the question

5. The figure below shows 2 balls ( red and blue) released from the same height at the same time with no initial vertical velocities. Which ball will hit the ground with the highest speed.

<img src="http://img177.imageshack.us/img177/8498/2ballsbuy0.gif"> [Broken]

My answer: both balls hit the ground at the same speed

choices:

a. The two balls will hit the ground with the same speed

b. The blue ball

c. The red ball

d. More information is needed to answer the question

7. A soccer ball is kicked from the ground and travels in the air as a projectile. Ignoring air resistance, which graph correctly represents the vertical velocity of the ball as a function of time?

<img src="http://img158.imageshack.us/img158/9913/pic1sr6.jpg"> [Broken]

My answer: A

choices:

a. A

b. B

c. C

10. A ball A is thrown off a cliff with an initial horizontal velocity. At the same time ball B is dropped with no initial velocity from the same height. Which ball has the largest speed upon hitting the ground?

My answer: the speeds are the same

choices:

a. A

b. B

c. The speeds are the same

d. Can't tell with the given information.

22. At the highest point of its trajectory a projectile has

a. zero acceleration and a constant horizontal velocity

b. zero vertical velocity and an acceleration equal to g

c. zero vertical velocity and a zero acceleration

My answer: A

choices:

a. zero acceleration and a constant horizontal velocity

b. zero vertical velocity and an acceleration equal to g

c. zero vertical velocity and a zero acceleration

23. If a ball is thrown at a 45 degree angle

a. it will reach the highest point it can ever reach

b. it will travel 100 m along the x axis

c. its initial horizontal and vertical velocities will be equal to each other

My answer: A

choices:

If a ball is thrown at a 45 degree angle

a. it will reach the highest point it can ever reach

b. it will travel 100 m along the x axis

c. its initial horizontal and vertical velocities will be equal to each other

31. A ball A is thrown at an angle with an initial vertical velocity of 5 m/s. At the same time a second ball B is thrown from the same height toward the ground ( vertically) with an initial velocity of -5 m/s. The two balls will hit the ground

a. at the same location but at different times

b. at the same time but at different locations

c. with the same vertical velocity but at different locations and different times

My answer: B

choices:

a. at the same location but at different times

b. at the same time but at different locations

c. with the same vertical velocity but at different locations and different times

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# Can someone please help me with these problems? New chapter start. 3-d motion

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