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Phy 201
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** CQ_1_13.1_labelMessages **
A ball rolls off the end of an incline with a vertical velocity of 20 cm/s downward, and a horizontal velocity of 80 cm/s. The ball falls freely to the floor 120 cm below.
• For the interval between the end of the ramp and the floor, hat are the ball's initial velocity, displacement and acceleration in the vertical direction?
Initial Velocity = 20 cm/s
Ds = 0 cm
a = 9.8 m/s^2
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• What therefore are its final velocity, displacement, change in velocity and average velocity in the vertical direction?
• V = V0 + at
• V = 20 cm/s + (9.8 m/s^2)(???? I can’t find any formulas that don’t require time, which is not given
• Ds = 120 cm
• A = 9.8 m/s^2
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You are given v0, a and `ds.
Which of the equations contains these three quantities?
There are two such equations. One includes the time interval, but the equation would be quadratic and I don't recommend solving that one. There's another equation you can use to get additional information, with which you will then easily be able to solve for t.
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• What are the ball's acceleration and initial velocity in the horizontal direction, and what is the change in clock time, during this interval?
• V0 = 80 cm/s
Dh = Vh*t
Dh = 80 cm/s * 0s = 0
There is no change in clock time, since you are calculating the initial velocity, which occurs at time zero.
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You are given v0, a and `ds.
Which of the equations contains these three quantities?
There are two such equations. One includes the time interval, but the equation would be quadratic and I don't recommend solving that one. There's another equation you can use to get additional information, with which you will then easily be able to solve for t.
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• What therefore are its displacement, final velocity, average velocity and change in velocity in the horizontal direction during this interval?
• ???? I’m not sure how to get the time, which is essential to get the other figures.
• To calculate the final velocity, I would use the formula vf = v0 + at. I would plug in the values for v0 and a, but since I don’t know how to determine t, I cannot proceed.
• To calculate the average velocity, I would use the formula a = (v - v0) / t, convert it to v = at + v0, and plug in my values for a and v0, since I don’t know how to get time, I cannot solve for v.
• Since I can’t find the final velocity, I can’t subtract the initial velocity from it to find hthe change in velocity.
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• After the instant of impact with the floor, can we expect that the ball will be uniformly accelerated?
• Yes
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• Why does this analysis stop at the instant of impact with the floor?
Balls can bounce in different directions or be otherwise affected by environmental factors.
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You've started on the right track. You need to identify and use the appropriate equation of motion to move forward. Check my note.
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