Table of contents

0. Math Review31m
- Math Review
  31m
1. Intro to Physics Units1h 29m
2. 1D Motion / Kinematics3h 56m
3. Vectors2h 43m
4. 2D Kinematics1h 42m
5. Projectile Motion3h 6m
6. Intro to Forces (Dynamics)3h 22m
7. Friction, Inclines, Systems2h 44m
8. Centripetal Forces & Gravitation7h 26m
9. Work & Energy1h 59m
10. Conservation of Energy2h 54m
11. Momentum & Impulse3h 40m
12. Rotational Kinematics2h 59m
13. Rotational Inertia & Energy7h 4m
14. Torque & Rotational Dynamics2h 5m
15. Rotational Equilibrium3h 39m
16. Angular Momentum3h 6m
17. Periodic Motion2h 9m
18. Waves & Sound3h 40m
19. Fluid Mechanics4h 27m
20. Heat and Temperature3h 7m
21. Kinetic Theory of Ideal Gases1h 50m
22. The First Law of Thermodynamics1h 26m
23. The Second Law of Thermodynamics3h 11m
24. Electric Force & Field; Gauss' Law3h 42m
25. Electric Potential1h 51m
26. Capacitors & Dielectrics2h 2m
27. Resistors & DC Circuits3h 8m
28. Magnetic Fields and Forces2h 23m
29. Sources of Magnetic Field2h 30m
30. Induction and Inductance3h 38m
31. Alternating Current2h 37m
32. Electromagnetic Waves2h 14m
33. Geometric Optics2h 57m
34. Wave Optics1h 15m
35. Special Relativity2h 10m

5. Projectile Motion

Intro to Projectile Motion: Horizontal Launch

Physics

5. Projectile Motion

Intro to Projectile Motion: Horizontal Launch

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Multiple Choice

Jim pushes a penny off a $0.86 m$ tall table. Assume the penny is moving horizontally as it leaves the table at 5 m/s. How long is the penny in the air? Ignore air resistance.

0.17 s

0.51 s

0.86 s

1.3 s

0.42 s

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Verified step by step guidance

Identify the type of motion: The penny is undergoing projectile motion, which consists of horizontal and vertical components. Since it is pushed off horizontally, the initial vertical velocity is zero.

Determine the vertical motion parameters: The height of the table is 0.86 m, and the acceleration due to gravity is approximately 9.81 m/s². The initial vertical velocity is 0 m/s.

Use the kinematic equation for vertical motion to find the time in the air: The equation is $ y = v_{i_y} t + \frac{1}{2} g t^2 $, where $ y $ is the vertical displacement (0.86 m), $ v_{i_y} $ is the initial vertical velocity (0 m/s), $ g $ is the acceleration due to gravity (9.81 m/s²), and $ t $ is the time in the air.

Simplify the equation: Since the initial vertical velocity is zero, the equation simplifies to $ y = \frac{1}{2} g t^2 $. Substitute the known values to get $ 0.86 = \frac{1}{2} \times 9.81 \times t^2 $.

Solve for $ t $: Rearrange the equation to solve for $ t $, which involves isolating $ t^2 $ and then taking the square root. This will give you the time the penny is in the air.