Solved Problems in Basic Physics

Electric circuits with resistors in parallel and internal resistance – problems and solutions

1. Based on the figure below, if the source of electromotive force (emf) is 24 Volt, determine electric current I.

Known : Electric circuits with resistors in parallel and internal resistance – problems and solutions 1

Source of emf = 24 Volt

Internal resistance (r) = 2 Ohm

Resistor 40 Ohm, 20 Ohm, and 20 Ohm.

Calculation of the electrical energy usage by electrical tool – problems and solutions

1. In a house, there are 5 lamps 25 Watt used 14 hours per day, a 200 Watt refrigerator used 24 hours per day, and a 125 Watt water pump used 8 hours per day. How much electrical energy used for a month (30 days)?

Known :

Power of lamp = 5(25) = 125 Watt and time of use = 14 hours x 30 = 420 hours

Power of refrigerator = 200 Watt and time of use = 24 hours x 30 = 720 hours

Power of water pump = 125 Watt and time of use = 8 hours x 30 = 240 hours

Types of electric charges – problems and solutions

1. Based on the figure of the electric charges below.

Objects A and D are negatively charged (-), object A attract object B and repels object C, object D repels E. Determine type of electric charge of object B, C, and E.

A. Positive, Positive, Negative

B. Negative, Negative, Positive

C. Positive, Negative, Negative

D. Positive, Negative, Positive

Simple machine (Inclined plane Lever) – Problems and Solutions

6 Simple machine (Inclined plane Lever) – Problems and Solutions

Simple machine (inclined plane, lever) - problems and solutions 1

Simple machine (inclined plane, lever) - problems and solutions 2

Which inclined plane have the same mechanical advantage

Nearsighted and farsighted – problems and solutions

1. A child with nearsighted can read a book at a near point 1 meter. In order to read at a normal reading distance of 25 cm, determine the power of the lens must use by the child.

Solution :

The child suffers farsighted, where the near point of his eyes is 1 meter or 100 cm. The near point of the normal eye is 25 cm. The eye can normalize by a convex lens.

Kinetic energy – problems and solutions

1. Two cars have the same mass, moving with different kinetic energy. The kinetic energy of the first car is 9 times the second car’s kinetic energy. The first car speed comparison with the second car is …..

Known :

Mass of car A (m_A) = m

Mass of car B (m_B) = m

The kinetic energy of car B (KE_B) = KE

The kinetic energy of car A (KE_A) = 9 KE