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

9. Work & Energy

Intro to Energy & Kinetic Energy

Physics

9. Work & Energy

Intro to Energy & Kinetic Energy

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Multiple Choice

Block A has mass $20 kg$ and block B has mass $50 kg$ . Starting from rest, the two blocks are pushed by identical forces through a distance of $10 m$ . Which block (if either) is going faster at end of the $10 m$ ? Which block (if either) has the greatest kinetic energy at the end of the $10 m$ ?

Both blocks will have the same final kinetic energy and the same final speed.

Block A will have a greater final kinetic energy and a greater final speed.

Block B will have a greater final kinetic energy and a greater final speed.

The blocks will have the same final kinetic energy, but block B will be moving faster.

The blocks will have the same final velocity, but block B will have greater kinetic energy.

The blocks will have the same final kinetic energy, but block A will be moving faster.

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Verified step by step guidance

Identify the forces acting on both blocks. Since the problem states that identical forces are applied to both blocks, we can denote this force as F.

Use the work-energy principle, which states that the work done on an object is equal to the change in its kinetic energy. The work done on each block is given by W = F * d, where d is the distance (10 m).

Since both blocks are pushed by the same force through the same distance, the work done on each block is the same. Therefore, the change in kinetic energy for both blocks is the same.

The kinetic energy (KE) of an object is given by the formula KE = (1/2) * m * v^2, where m is the mass and v is the velocity. Since the change in kinetic energy is the same for both blocks, we can set up the equation: (1/2) * m_A * v_A^2 = (1/2) * m_B * v_B^2.

Solve for the velocities v_A and v_B. Since block A has a smaller mass, it must have a higher velocity to have the same kinetic energy as block B. Therefore, block A will be moving faster, but both blocks will have the same kinetic energy.