Gravitation — Practice Quiz

Because the Moon's mass is smaller and radius is smaller, making g on Moon = g on Earth/6

Step 1: Weight depends on the value of g, which varies with the celestial body's mass and radius (g = GM/R²). Step 2: The Moon's mass (7.36×10²² kg) is much smaller than Earth's mass (5.98×10²⁴ kg). Step 3: The Moon's radius (1.74×10⁶ m) is also smaller than Earth's radius (6.37×10⁶ m). Step 4: When we calculate g for the Moon using its mass and radius, we get approximately g_moon = g_earth/6. Step 5: Since W = mg, an object weighs 1/6th on the Moon compared to Earth. Options B, C, and D are unrelated to gravitational acceleration and don't explain the weight difference.

The force acting perpendicular to the surface

Step 1: Thrust is defined as the component of force that acts perpendicular (at 90°) to a surface. Step 2: When you press a drawing pin into a board, the force you apply acts perpendicular to the pin's head - this is thrust. Step 3: Thrust is measured in Newtons (N), the same unit as force. Step 4: The effectiveness of thrust depends on the area over which it acts, leading to the concept of pressure. Step 5: Examples include the force a rocket engine exerts perpendicular to its nozzle or your weight acting perpendicular to the ground. Option B describes a different force component. Option C de

Thrust per unit area

Step 1: Pressure is the physical quantity that measures how much thrust (perpendicular force) is applied per unit area. Step 2: It is calculated using the formula: Pressure = Thrust/Area = F/A. Step 3: The SI unit of pressure is Pascal (Pa), which equals N/m². Step 4: Same force applied over smaller area creates higher pressure (like a nail's pointed tip). Step 5: Examples include atmospheric pressure, blood pressure, or pressure from your feet on the ground. Option B describes a different force component. Option C defines density. Option D describes weight, which is a force, not pressure.

The upward force exerted by a fluid on an immersed object

Step 1: Buoyant force (or buoyancy) is the upward force that a fluid (liquid or gas) exerts on any object placed in it. Step 2: This force arises because fluid pressure increases with depth, creating higher pressure at the bottom of the object. Step 3: You can feel this force when trying to push a plastic bottle underwater - it pushes back upward. Step 4: Buoyant force makes objects feel lighter when immersed in water. Step 5: This force can make objects float if it equals or exceeds the object's weight. Option B describes gravitational force, not buoyant force. Option C describes net downward