9th Grade Physics Olympiad

Solution

Correct: B

Acceleration is the change in velocity divided by the time taken. Here, acceleration = (20 m/s - 0 m/s) / 5 s = 4 m/s².

Solution

Correct: C

The SI unit of force is the Newton (N), which is defined as kg*m/s².

Solution

Correct: B

Potential energy is stored energy. A stretched rubber band has potential energy due to its deformation. The energy is released when the rubber band is let go.

Solution

Correct: C

Newton's first law (the law of inertia) states that an object in motion stays in motion with the same speed and in the same direction unless acted upon by a force.

Solution

Correct: C

Rubbing hands together converts mechanical energy (the motion of your hands) into thermal energy (heat) due to friction.

Solution

Correct: C

Momentum is calculated as mass times velocity (p = mv). In this case, p = 2 kg * 3 m/s = 6 kg m/s.

Solution

Correct: C

Sound waves are mechanical waves and require a medium (solid, liquid, or gas) to propagate. Electromagnetic waves like radio, microwaves, and light can travel through a vacuum.

Solution

Correct: B

Frequency and wavelength are inversely proportional. As frequency increases, wavelength decreases, and vice-versa, maintaining a constant wave speed.

Solution

Correct: B

According to Newton's second law (F = ma), acceleration (a) = Force (F) / mass (m). Therefore, a = 10 N / 2 kg = 5 m/s².

Solution

Correct: B

The acceleration due to gravity on Earth is approximately 9.8 m/s². This means that for every second an object falls, its velocity increases by 9.8 m/s.

Solution

Correct: D

The law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. Energy can neither be created nor destroyed, but can transform from one form to another.

Solution

Correct: B

The relationship between wave speed (v), frequency (f), and wavelength (λ) is v = fλ. Therefore, wavelength λ = v / f = 10 m/s / 5 Hz = 2 m.

Solution

Correct: A

Inertia is the tendency of an object to resist changes in its state of motion. Inertia is directly proportional to mass; therefore, increasing the mass increases the inertia.

Solution

Correct: C

A vector quantity has both magnitude and direction. Velocity is a vector quantity, whereas speed is a scalar quantity (magnitude only).

Solution

Correct: B

Potential energy (PE) is calculated as PE = mgh, where m is mass, g is the acceleration due to gravity, and h is height. PE = 5 kg * 9.8 m/s² * 10 m = 490 J.

Solution

Correct: D

Violet light has the shortest wavelength in the visible spectrum. The order of wavelengths from longest to shortest is Red, Orange, Yellow, Green, Blue, Indigo, Violet.

Solution

Correct: B

Nearsightedness (myopia) is corrected using concave lenses. These lenses diverge light rays before they enter the eye, helping to focus the image correctly on the retina.

Solution

Correct: C

Work is calculated as Force times Distance (W = Fd). Therefore, W = 20 N * 5 m = 100 J.

Solution

Correct: C

Copper is a good conductor of electricity because it has free electrons that can easily move and carry electrical charge. Rubber, glass, and wood are insulators.

Solution

Correct: C

Kinetic energy (KE) is calculated as KE = 1/2 * mv², where m is mass and v is velocity. Therefore, KE = 1/2 * 10 kg * (5 m/s)² = 1/2 * 10 kg * 25 m²/s² = 125 J.