Mass, Weight & Density

The SI unit for mass is Kilogram (Kg). The kilogram is the base unit of mass in the International System of Units (SI) and is defined as the mass of the International Prototype of the Kilogram, a platinum-iridium cylinder kept at the International Bureau of Weights and Measures. It is widely used in scientific and everyday measurements of mass.

When an astronaut is on the Moon, they experience less weight but the same mass as on the Earth. Weight is the force of gravity acting on an object, and since the Moon has less gravitational pull compared to the Earth, the astronaut's weight is reduced. However, mass is a measure of the amount of matter in an object, and it remains the same regardless of the gravitational pull. Therefore, the astronaut's mass remains the same on the Moon as it is on the Earth, but they weigh less due to the weaker gravity.

The SI unit for weight is Newton. Weight is a force that is exerted on an object due to the gravitational pull of the Earth or any other celestial body. The Newton is defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared. Therefore, the Newton is the appropriate SI unit for measuring weight, as it represents the force exerted on an object due to gravity.

The SI unit for density is kg/m3 because density is defined as mass per unit volume. In this unit, the mass is measured in kilograms (kg) and the volume is measured in cubic meters (m3). This unit allows for a consistent and standardized measurement of density across different substances and systems.

The correct answer is that the rock is easier to push than on Earth. This is because the force of gravity on the Moon is only about 1/6th of the force of gravity on Earth. Therefore, the weight of the rock is much less on the Moon, making it easier to push.

A spring balance is an instrument used to measure weight. It consists of a spring that stretches or compresses based on the weight applied to it. The amount of stretch or compression is directly proportional to the weight, allowing for accurate measurement. This makes a spring balance a reliable tool for measuring weight in various applications.

The density of a substance is calculated by dividing its mass by its volume. In this case, the mass of the container and liquid is given as 70g, and the volume of the liquid is given as 40cm3. To find the density of the liquid, we divide the mass (70g) by the volume (40cm3), which gives us 1.75 g/cm3. However, the answer choices do not include this value. Therefore, it seems that there is an error in the question or answer choices.

Since the question states that both sack X and sack Y contain 10 kg of material, it can be inferred that they have the same weight. The question does not provide any information about the volume of the sacks or the density of the materials, so we cannot determine which sack has a larger volume or which sack is denser. Therefore, the correct answer is that sack Y has the same weight as sack X.

The weight of an object is determined by the gravitational force acting on it. The weight of the rock on the Moon is 400N, which means that the gravitational force on the rock on the Moon is 400N. Given that the gravitational field on the Moon is 1.7N/Kg, we can calculate the mass of the rock on the Moon by dividing the weight by the gravitational field: mass = weight / gravitational field = 400N / 1.7N/Kg = 235.29 Kg.

Now, to find the weight of the rock on Earth, we use the gravitational field on Earth, which is 10N/Kg. Weight = mass * gravitational field = 235.29 Kg * 10N/Kg = 2352.9N. Rounding to the nearest whole number, we get 2350N as the weight of the rock on Earth.

The mass of air in the room can be calculated by multiplying the volume of the room by the density of the air. The volume of the room is obtained by multiplying its length, width, and height. In this case, the volume of the room is 4.0m x 3.0m x 2.0m = 24 cubic meters. Multiplying this volume by the density of the air (1.3kg/m3), we get 24 cubic meters x 1.3kg/m3 = 31.2 kg. 

The density of an object is calculated by dividing its mass by its volume. In this question, the initial cube has a mass of 7500 kg and a volume of (1 m)^3 = 1 m^3. After drilling the hole and filling it with cement, the volume of the composite object remains 1 m^3. The mass of the cement can be calculated by multiplying its density (3.2 g/cm^3) by its volume (pi * (0.25 m)^2 * 1 m = 0.19634954 m^3) and converting it to kg (0.19634954 m^3 * 3.2 g/cm^3 * 1000 kg/g = 627.678528 kg). Therefore, the total mass of the composite object is 7500 kg + 627.678528 kg = 8127.678528 kg. Dividing this mass by the volume (1 m^3), the density of the composite object is 8127.678528 kg/m^3, which is not listed among the answer choices.