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Exercise 3: Ball Thrown Up

Instead of dropping the object from the height of 1.0 m, let’s imagine you throw the object straight up into the air. Think about what happens to the ball the second after it has left your hand and is moving up versus the second before it returns to your hand and is moving down, which is described by the first and second scenarios depicted in the table below. For this exercise, we will set our coordinate system so that the origin is at the ground and upwards is the positive direction. Note: We are not taking any measurements with this exercise but discussing things qualitatively.

Exercise 3.1 (1 mark)

Fill in the chart by circling one of each:

+ (positive) / 0 (zero) / – (negative)

and

↑ (increasing with time) / ↓ (decreasing with time) / c (constant with time)

Remember: Velocity and acceleration have a magnitude and direction.

On Crowdmark choose the correct version(s) of the table.

A 3 by 5 chart. The first row reads: observation, position, velocity, speed, and acceleration. In the first cell of the second row, we are observing a scenario where a ball is moving upwards just after leaving a hand. In the cell to the right, we are then asked to determine if the position is positive, 0, or negative, in the next cell to the right if the velocity is positive, 0, or negative, in the next cell to the right if the speed is up, down, or constant, and finally in the next cell to the right, if the acceleration is positive, 0, or negative. The first cell of the third row considers the scenario just before the ball returns to the hand, moving in the downward direction. The same questions are posed: in the cell to the right, determine if the position is positive, 0, or negative, in the cell to the right, determine if the velocity is positive, 0, or negative, in the cell t the right, determine if the speed is up, down, or constant, and finally, in the cell to the right, determine if the acceleration is positive, 0, or negative.

Exercise 3.2 (1 mark)

Using the concept of vectors and referring to your coordinate system, choose the best description of what happens to the velocity and speed just before the object returns to your hand (the highlighted cells in the above chart). Choose the correct answer(s) on Crowdmark.

a. The velocity is zero and the speed is decreasing since the object is experiencing a constant negative acceleration.

b. The velocity is negative and the speed is decreasing since the object is experiencing a constant positive acceleration.

c. The velocity is positive and the speed is constant.

d. The velocity is zero and the speed is increasing since the object is experiencing a constant negative acceleration.

e. The velocity is negative and the speed is increasing since the object is experiencing a constant negative acceleration.

 

Before you continue!

Before continuing, be sure you have completed Exercises 3.1 and 3.2 on Crowdmark for grading.

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Introductory Physics Labs - OER Development Copyright © by Physics 1A03 Team is licensed under a Ontario Commons License – No Derivatives, except where otherwise noted.

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