Multiple Choice
In ideal projectile motion (neglecting air resistance), an object launched horizontally from a height will follow which path?
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5. Projectile Motion
Intro to Projectile Motion: Horizontal Launch
Multiple Choice
A rock is thrown horizontally with a speed of 20 m/s from the edge of a high cliff. It lands 80 m from the cliff's base. How tall is the cliff?
A
78.4 m
B
19.6 m
C
122.5 m
D
24.5 m
Verified step by step guidance1
Identify the known values: the horizontal speed of the rock is 20 m/s, and the horizontal distance it travels is 80 m.
Use the formula for horizontal motion to find the time of flight: \( t = \frac{d}{v} \), where \( d \) is the horizontal distance (80 m) and \( v \) is the horizontal speed (20 m/s).
Calculate the time of flight using the formula: \( t = \frac{80}{20} \).
Use the time of flight to find the height of the cliff using the formula for vertical motion: \( h = \frac{1}{2} g t^2 \), where \( g \) is the acceleration due to gravity (9.8 m/s²).
Substitute the time of flight into the vertical motion formula to calculate the height: \( h = \frac{1}{2} \times 9.8 \times t^2 \).
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