IGCSE Physics Exam Quiz! Trivia

Explanation
The half-life of a radioactive substance is the time it takes for half of the substance to decay. In this case, the half-life is 5 hours. Since 20 hours have passed before the sample was tested, we can calculate how many half-lives have occurred. 20 divided by 5 is 4, so 4 half-lives have occurred. Each half-life reduces the amount of substance by half, so after 4 half-lives, the amount of substance remaining would be 1/2^4 = 1/16 of the original amount. Therefore, the amount of substance present in the sample 20 hours before testing would be 0.48g * 1/16 = 0.03g.

Explanation
The power of the motor can be calculated using the formula: Power = Work Done / Time Taken. Therefore, knowing the work done and the time taken is enough to calculate the power of the motor.

Explanation
Inertia refers to the reluctance of an object to change its state of rest or motion. It is a property of matter that causes objects to resist any change in their velocity. The greater the mass of an object, the greater its inertia, meaning it will require more force to accelerate or decelerate. Inertia is a fundamental concept in physics and is closely related to Newton's first law of motion, which states that an object at rest will stay at rest, and an object in motion will stay in motion, unless acted upon by an external force.

Explanation
Pressure is defined as the force exerted over a given area. When a force is applied to an object, it creates pressure by distributing the force over the surface area. The greater the force applied or the smaller the area, the higher the pressure. Therefore, force is the correct answer as it directly relates to the definition of pressure in physics.

Explanation
The standard unit of measure for pressure is the Pascal. The Pascal is defined as one Newton per square meter, representing the amount of force exerted on a surface area. This unit is widely used in scientific and engineering fields to quantify pressure, such as in fluid dynamics, weather forecasting, and mechanical engineering.

Explanation
Air pressure will be higher on the beach compared to the top of a mountain. This is because air pressure decreases with increasing altitude. As we go higher in the atmosphere, there is less air above us, resulting in lower air pressure. On the beach, we are closer to sea level, where there is more air above us, leading to higher air pressure.

Explanation
The pressure exerted by an object is calculated by dividing the force exerted by the area over which it is applied. In this case, the block exerts a force of 40 N and the pressure is 20 Pa. To find the area, we can rearrange the formula to area = force/pressure. Plugging in the values, we get area = 40 N / 20 Pa = 2 meters squared. Therefore, the area of the block that is touching the table is 2 meters squared.

Explanation
A barometer is a tool used to measure air pressure. It consists of a glass tube filled with mercury or a liquid, with one end sealed and the other end open. As the air pressure changes, it causes the liquid in the tube to rise or fall. By measuring this change in liquid level, the barometer can determine the air pressure. The other options listed - Pascalometer, Atmospherometer, Aerometer, and Anemometer - are not commonly used tools for measuring air pressure.

Explanation
Joule is not a unit of measure for pressure because it is a unit of energy or work. Pressure is defined as force per unit area, and is typically measured in units such as PSI (pounds per square inch), bar, or atmosphere. Joule, on the other hand, is a unit used to measure energy or work done. Therefore, it is not a suitable unit for measuring pressure.

Explanation
As you go deeper into the water, the weight of the water above you increases, resulting in an increase in water pressure. This is because the force exerted by the water molecules above you becomes greater. Therefore, the correct answer is "Increase."