Lecture 6

Summary

Kinematic equations
Freefall
Two-dimensional motion

Written Quiz Chs.01-02

Projectiles

independent motions
Ball on moving cart video
Ping pong ball model video

Level ground formulas

Interactive applet
BU projectile applet 1

This applet shows the motion of a projectile and allows you to simultaneously graph one of 7 different quantities. It doesn't let you change the launch angle directly, but you can change the v_0x and v_0y components.

horizontal range
maximum height

Example #1

Example #2

Example #3

Compare ranges applet
BU projectile applet 2

This applet displays the trajectory of 16 projectiles simultaneously, allowing you to see the effect of different launch angles and graph the maximum heights, times of flight, and horizontal ranges of all 16 projectiles.

Zero gravity line demonstration video

Walker5e 4.30
A cannonball is launched at an angle above level ground, giving it an initial vertical and horizontal velocity that are each positive. The cannonball lands at a time T after it is launched. Plot _____ in the figure below best represents the horizontal component of the cannonball's velocity and plot ______ best represents the vertical component of the cannonball's velocity. various plots of velocity versus time

A. C ... B
B. A ... B
C. A ... E
D. B ... D
Answer

sb5 4.13
A shell is fired at 300 m/s with an elevation angle of 55°. It lands on a mountainside 42.0 s after firing. At what elevation above the gun does it land?
A. 1680 m
B. 7230 m
C. 9450 m
D. 10,320 m
Answer

sb5 4.55
A boy can throw a ball a maximum horizontal distance of 40.0 m over level ground. How high vertically upward can he throw it?
A. 10.0 m
B. 20.0 m
C. 30.0 m
D. 40.0 m
Answer

answer
various plots of velocity versus time

C. A ... E

The horizontal component of the velocity is positive and constant, and the vertical component of the velocity starts positive but then decreases at a rate of −9.80 m/s², becoming negative as the cannonball passes the highest point of its trajectory.

answer

A. 1680 m

answer

B. 20.0 m