CSS - PMS - CCE - PCS - General Science
Modern Physics - Atom
Which model introduced quantized electron energy levels for hydrogen?
A. Fluid model
B. Bohr model
C. Plum pudding model only
D. Dalton solid-sphere model only
Correct Answer: B
Bohr proposed discrete electron orbits/energy levels for hydrogen.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Atom
What particles are found in the atomic nucleus?
A. Electrons only
B. Ions only
C. Protons and neutrons
D. Photons only
Correct Answer: C
The nucleus is composed of nucleons: protons and neutrons.
CSS - PMS - CCE - PCS - General Science
Modern Physics - Atom
What is an atom?
A. A visible dust particle only
B. The smallest unit of an element that retains its chemical identity
C. A molecule made of many elements only
D. A proton with no electrons always
Correct Answer: B
Atoms contain nuclei and electrons and define chemical elements by proton number.
CSS - PMS - CCE - PCS - General Science
Mechanics - Work & Energy
What does conservation of energy state?
A. Energy can be created from nothing
B. Energy cannot be created or destroyed, only transferred or transformed in an isolated system
C. Energy equals mass only
D. Energy always disappears
Correct Answer: B
Total energy is conserved though it may change form.
CSS - PMS - CCE - PCS - General Science
Mechanics - Work & Energy
What is gravitational potential energy near Earth's surface?
A. PE = Q/t
B. PE = mgh
C. PE = V/I
D. PE = 1/2 mv²
Correct Answer: B
For approximately uniform gravity, potential energy change is mgh.
CSS - PMS - CCE - PCS - General Science
Mechanics - Work & Energy
What is the formula for translational kinetic energy?
A. KE = mv
B. KE = mgh
C. KE = 1/2 mv²
D. KE = F/A
Correct Answer: C
Classical kinetic energy is one-half mass times speed squared.
CSS - PMS - CCE - PCS - General Science
Mechanics - Work & Energy
What is kinetic energy?
A. Energy due only to height
B. Energy due to motion
C. No form of energy
D. Energy stored only chemically
Correct Answer: B
Kinetic energy depends on mass and speed.
CSS - PMS - CCE - PCS - General Science
Mechanics - Work & Energy
What is the SI unit of work and energy?
A. Watt
B. Joule
C. Newton
D. Pascal
Correct Answer: B
Work and energy are measured in joules.
CSS - PMS - CCE - PCS - General Science
Mechanics - Work & Energy
What is mechanical work?
A. Temperature change only
B. Energy transferred when a force causes displacement in its direction
C. Force with no displacement always
D. Mass multiplied by time
Correct Answer: B
For constant force, W = Fd cosθ.
CSS - PMS - CCE - PCS - General Science
Mechanics - Speed & Velocity
If a car travels 100 km in 2 h, its average speed is what?
A. 102 km/h
B. 200 km/h
C. 50 km/h
D. 25 km/h
Correct Answer: C
Average speed equals total distance divided by total time.
CSS - PMS - CCE - PCS - General Science
Mechanics - Speed & Velocity
Which quantity is vector?
A. Speed
B. Distance
C. Time
D. Velocity
Correct Answer: D
Velocity includes both magnitude and direction.
CSS - PMS - CCE - PCS - General Science
Mechanics - Speed & Velocity
Which quantity is scalar?
A. Acceleration
B. Displacement
C. Speed
D. Velocity
Correct Answer: C
Speed has magnitude but no direction.
CSS - PMS - CCE - PCS - General Science
Mechanics - Speed & Velocity
What is the SI unit of speed and velocity?
A. J
B. m/s²
C. N
D. m/s
Correct Answer: D
Both are measured in meters per second.
CSS - PMS - CCE - PCS - General Science
Mechanics - Speed & Velocity
What is velocity?
A. Power per unit area
B. Mass per unit time
C. Distance only with no direction
D. Rate of change of displacement with direction
Correct Answer: D
Velocity is a vector quantity.
CSS - PMS - CCE - PCS - General Science
Mechanics - Speed & Velocity
What is speed?
A. Energy per unit charge
B. Displacement with direction only
C. Force per unit mass
D. Distance traveled per unit time
Correct Answer: D
Speed is a scalar rate of distance traveled.
CSS - PMS - CCE - PCS - General Science
Mechanics - Power
For constant force parallel to velocity, power can be written as what?
A. P = mv
B. P = Fv
C. P = v/F
D. P = F/v
Correct Answer: B
Instantaneous mechanical power is force dot velocity.
CSS - PMS - CCE - PCS - General Science
Mechanics - Power
If 200 J of work is done in 10 s, what is the average power?
A. 20 W
B. 210 W
C. 2000 W
D. 2 W
Correct Answer: A
P = 200/10 = 20 W.
CSS - PMS - CCE - PCS - General Science
Mechanics - Power
How many joules per second equal one watt?
A. 100
B. 1000
C. 1
D. 10
Correct Answer: C
By definition, 1 W = 1 J/s.
CSS - PMS - CCE - PCS - General Science
Mechanics - Power
Which formula gives average power?
A. P = m/v
B. P = W×t
C. P = W/t
D. P = F/A
Correct Answer: C
Average power is work divided by time.
CSS - PMS - CCE - PCS - General Science
Mechanics - Power
What is the SI unit of power?
A. Newton
B. Pascal
C. Watt
D. Joule
Correct Answer: C
One watt equals one joule per second.