Physics_Projectile Motion Virtual Experiment

Physics_Projectile Motion Virtual Experiment

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Essential Question

How does kinematics apply in practical  situations involving the motion of rigid bodies?

Part A: Horizontally Launched Projectile

Objectives:

·      I can relate the initial velocity of a horizontally launched projectile to its total airtime and to its range.

·      I can relate the height of launch of a horizontally launched projectile to its total airtime and to its range.

RECALL QUESTIONS: VIRTUAL LAB

Be ready to answer the following questions based on the virtual experiment on Projectile Motion!

Multiple Choice

RECALL QUESTION: How does the change in the initial horizontal velocity affect the total airtime of the projectile?

• no effect

• greater initial horizontal velocity = more airtime

• greater initial horizontal velocity = less airtime

ANSWER:

The horizontal velocity quantifies how fast the projectile progresses along the x-axis, but not the y-axis, hence, it does not affect how fast the object reaches the ground. Airtime isn't affected by the variations in the horizontal velocity as long as other variables are held constant.

Multiple Choice

RECALL QUESTION: How does the change in the initial horizontal velocity affect the range of the projectile?

• no effect

• greater initial horizontal velocity = greater range

• greater initial horizontal velocity = less range

ANSWER:

Range refers to the displacement covered by the projectile along the x-axis. The initial horizontal velocity tells us how fast the object moves along the x-axis per unit time. Therefore, with all other variables held constant, greater horizontal velocity results to greater range.

Multiple Choice

RECALL QUESTION: How does the height of launch affect the total airtime of the projectile?

• no effect

• greater launching height = greater airtime

• greater launching height = less airtime

Multiple Choice

RECALL QUESTION: How does the height of launch affect the range of the projectile?

• no effect

• greater launching height = greater range

• greater launching height = smaller range

ANSWER:

Launching the projectile at a greater height allows it to stay longer in the air, hence, allowing it to cover greater range as well.

Part B: Projectile Launched at an Angle

Objective:

·      I can relate the angle of projection with the total airtime, maximum height, and range of a projectile.

Multiple Choice

RECALL QUESTION: How does the angle of projection affect the total airtime and maximum height of the projectile?

• no effect

• greater angle of projection = more airtime = greater maximum height

• greater angle of projection = less airtime = smaller maximum height

ANSWER:

Launching the projectile towards higher angles gives a greater velocity magnitude along the vertical axis (greater v_0y). Greater vertical component of velocity of a projectile would mean it will take longer for gravity to slow it down and stop its motion along the y-axis. This results to longer airtime and greater maximum height.

Open Ended

What do you notice in the range of the projectile as the angle of projection is varied? At what angle is the maximum range achieved?

ANSWER:

Approaching the 45-degree angle from zero, the range of the projectile increases. But from the 45-degree angle towards 90-degrees, the range decreases. The maximum range is achieved when the projectile is launched at a 45-degree angle. Complementary angles (e.g. 30 and 60 degrees) result to the same range.

CONCEPT CHECK

Be ready to answer a few conceptual questions in the following slides...

Multiple Select

Refer to the image shown. Suppose your goal is to hit the red, center circle in the target. If the trajectory shown was your first attempt (failed), which of the following could give you a better chance in your second attempt? Check the step/s that could work (not necessarily all together, but as individual interventions).

• increase the initial velocity

• decrease the initial velocity

• increase the angle

• decrease the angle

Multiple Select

Refer to the image shown. Suppose your goal is to hit the red, center circle in the target. If the trajectory shown was your first attempt (failed), which of the following could give you a better chance in your second attempt? Check the step/s that could work (not necessarily all together, but as individual interventions).

• increase the initial velocity

• decrease the initial velocity

• increase the angle

• decrease the angle

Multiple Select

Refer to the image shown. Suppose your goal is to hit the red, center circle in the target. If the trajectory shown was your first attempt (failed), which of the following could give you a better chance in your second attempt? Check the step/s that could work (not necessarily all together, but as individual interventions).

• increase the initial velocity

• decrease the initial velocity

• increase the angle

• decrease the angle

Open Ended

A boy on a small hill aims his water balloon slingshot horizontally, straight at a second boy hanging from a tree branch at a distance away. To avoid being hit, what should the second boy do as the water balloon is released?

A. keep hanging on the tree

B. let go and fall from the tree

Explain your answer as briefly as possible using relevant kinematics concepts.

IMAGE CREDITS

Giancoli, D. Physics, 6th edition (2007). Pearson Education Inc.

Projectile Motion, https://phet.colorado.edu