CSS - PMS - CCE - PCS - General Science
Mechanics - Friction
Why is friction useful for walking?
A. It causes floating
B. It provides traction between foot and ground
C. It removes gravity
D. It eliminates mass
Correct Answer: B
Static friction allows the foot to push backward on the ground while the ground pushes the person forward.
CSS - PMS - CCE - PCS - General Science
Mechanics - Friction
How can friction between moving machine parts often be reduced?
A. Roughening surfaces strongly
B. Increasing normal force
C. Lubrication
D. Removing all bearings
Correct Answer: C
Lubricants separate surfaces and reduce direct contact.
CSS - PMS - CCE - PCS - General Science
Mechanics - Friction
Which friction acts when surfaces slide past each other?
A. Buoyant force
B. Kinetic friction
C. Static friction
D. Magnetic force
Correct Answer: B
Kinetic or sliding friction opposes ongoing sliding motion.
CSS - PMS - CCE - PCS - General Science
Mechanics - Friction
Which friction acts before sliding begins?
A. Fluid drag only
B. Kinetic friction
C. Rolling resistance only
D. Static friction
Correct Answer: D
Static friction adjusts up to a limiting value to prevent relative sliding.
CSS - PMS - CCE - PCS - General Science
Mechanics - Friction
What is friction?
A. A force that always increases motion
B. A force that opposes relative motion or tendency of motion between surfaces in contact
C. A form of temperature
D. A type of mass
Correct Answer: B
Friction acts tangentially at contact surfaces.
CSS - PMS - CCE - PCS - General Science
Mechanics - Acceleration
What is negative acceleration often called when it reduces speed along the chosen positive direction?
A. Velocity
B. Momentum
C. Power
D. Deceleration
Correct Answer: D
Deceleration is informal terminology for acceleration opposite the direction of motion.
CSS - PMS - CCE - PCS - General Science
Mechanics - Acceleration
What is the approximate acceleration due to gravity near Earth's surface?
A. 9.8 m/s²
B. 0 m/s²
C. 98 m/s²
D. 1 m/s²
Correct Answer: A
Near Earth's surface, g is about 9.8 m/s² downward.
CSS - PMS - CCE - PCS - General Science
Mechanics - Acceleration
Can an object moving at constant speed have acceleration?
A. Only if mass changes
B. No, never
C. Only at rest
D. Yes, if its direction changes
Correct Answer: D
Velocity includes direction, so uniform circular motion has acceleration.
CSS - PMS - CCE - PCS - General Science
Mechanics - Acceleration
Which formula gives average acceleration?
A. a = F×m
B. a = P/t
C. a = Δv/Δt
D. a = d/t
Correct Answer: C
Average acceleration equals change in velocity divided by time interval.
CSS - PMS - CCE - PCS - General Science
Mechanics - Acceleration
What is the SI unit of acceleration?
A. m/s
B. N
C. J
D. m/s²
Correct Answer: D
Acceleration is velocity change per second.
CSS - PMS - CCE - PCS - General Science
Mechanics - Acceleration
What is acceleration?
A. Rate of change of mass
B. Distance divided by mass
C. Force per unit area
D. Rate of change of velocity with time
Correct Answer: D
Acceleration describes how velocity changes.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Reflection
Does diffuse reflection obey the law of reflection locally?
A. Only for red light
B. Only in vacuum
C. Yes
D. No, never
Correct Answer: C
Each microscopic surface patch obeys the law of reflection even though the overall pattern is diffuse.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Reflection
What is diffuse reflection?
A. Refraction through glass
B. Total absence of reflection
C. Only reflection from mirrors
D. Scattering of reflected light in many directions from a rough surface
Correct Answer: D
Microscopic surface irregularities redirect incident rays in different directions.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Reflection
What is regular reflection?
A. No reflection
B. Reflection from a smooth surface producing parallel reflected rays from parallel incident rays
C. Scattering in all directions
D. Reflection only from rough surfaces
Correct Answer: B
Smooth surfaces preserve ray order and can form clear images.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Reflection
From what line are angles of incidence and reflection measured?
A. The normal to the surface
B. The surface itself only
C. The light source
D. The horizon
Correct Answer: A
Optics convention measures these angles relative to the normal.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Reflection
What is the law of reflection?
A. Angles are always 90°
B. Angle of incidence is twice reflection
C. Reflected light has no angle
D. Angle of incidence equals angle of reflection
Correct Answer: D
Both angles are measured from the normal.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Reflection
What is reflection of light?
A. Bending of light in a new medium
B. Splitting an atom
C. Absorption only
D. Bouncing back of light from a surface
Correct Answer: D
Reflection changes light direction at a surface.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Optical Instruments
What is the objective lens in a microscope mainly responsible for?
A. Controlling room temperature
B. Generating sound
C. Measuring voltage
D. Producing the primary magnified image of the specimen
Correct Answer: D
The objective provides most of the microscope's optical resolution and initial magnification.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Optical Instruments
Which device separates white light into a spectrum?
A. Barometer
B. Ammeter
C. Thermometer
D. Prism or diffraction grating
Correct Answer: D
Dispersion or diffraction can separate wavelengths of visible light.
CSS - PMS - CCE - PCS - General Science
Light (Optics) - Optical Instruments
What optical principle is used in a periscope?
A. Radioactivity
B. Conduction
C. Reflection
D. Electrical induction
Correct Answer: C
Periscopes use mirrors or prisms to redirect light.