Physics Quiz: Laws Of Motion And Gravitation Questions!

Explanation
The acceleration in a body is due to unbalanced force. When there is an unbalanced force acting on an object, it causes a change in the object's motion, resulting in acceleration. An unbalanced force occurs when the forces acting on an object are not equal in magnitude and opposite in direction, causing a net force that leads to acceleration.

Explanation
Force is the physical quantity that is equal to the rate of change of momentum. Newton's second law states that force is equal to the rate of change of momentum, which means that when a force is applied to an object, its momentum changes. Therefore, force is directly proportional to the rate of change of momentum, making it the correct answer in this case.

Explanation
The momentum of a massive object at rest is zero. When an object is at rest, it has no velocity, and momentum is defined as the product of mass and velocity. Since the velocity is zero, the momentum of the object is also zero.

Explanation
The weight of a person is determined by the force of gravity acting on their mass. On the surface of the earth, the acceleration due to gravity is approximately 9.8 m/s^2. To calculate the weight, we use the formula W = m * g, where W is the weight, m is the mass, and g is the acceleration due to gravity. In this case, the person has a mass of 50 kg, so the weight would be 50 kg * 9.8 m/s^2 = 490 N.

Explanation
Biotechnology products like vaccines require nitrogen freezing systems because nitrogen is an inert gas that can maintain extremely low temperatures without reacting with the products. Nitrogen freezing systems provide a controlled and stable environment for freezing biotechnology products, ensuring their integrity and effectiveness. Helium, ammonia, and chlorine are not commonly used for freezing biotechnology products due to their reactive nature or unsuitability for maintaining low temperatures.

Explanation
The mass of an object is a fundamental quantity that represents the amount of matter in the object. It is not dependent on the method of measurement, whether it is measured using a physical balance or a spring balance. The mass remains the same regardless of the type of balance used. Therefore, the statement "It is measured using spring balance" is not applicable to the mass of an object.

Explanation
The equation for momentum is derived from the equation for force, which is force = mass x acceleration. Since momentum is defined as mass multiplied by velocity, the correct answer is mass x velocity.

Explanation
Liquid helium is used for MRI machines. MRI machines use strong magnetic fields and radio waves to generate images of the body's internal structures. Liquid helium is used to cool the superconducting magnets in the MRI machine, allowing them to operate at extremely low temperatures and maintain their superconducting properties. This is necessary for the magnets to generate the strong and stable magnetic field required for the imaging process. Liquid hydrogen, on the other hand, is used as rocket fuel due to its high energy density and ability to provide a powerful thrust.

Explanation
BARC is the wrong organization associated with the Chandrayan-I mission. The correct organizations associated with the mission are ISRO, NASA, and ESA. BARC, which stands for Bhabha Atomic Research Centre, is not directly involved in space exploration and is not associated with the Chandrayan-I mission.

Explanation
An anticlockwise moment is conventionally taken as positive because it is considered to be in the same direction as the positive x-axis in a Cartesian coordinate system. On the other hand, a clockwise moment is conventionally taken as negative because it is considered to be in the opposite direction of the positive x-axis.