(a)
For the correct answer:
(42 – 30 = ) 12 \(cm^3\)
The volume of an irregularly shaped solid that sinks can be found by the displacement method. The initial volume of water is \(30 cm^3\). After submerging the metal, the new volume is \(42 cm^3\). The volume of the metal is the difference between these two readings.
(b)
For the correct answer:
\(( \rho =)\) 8(.0)
\(( \rho =)\) 320 ÷ 40
(density =) mass ÷ volume OR \(( \rho =)\) m / V in any form
\(g / cm^3\)
Density is defined as mass per unit volume, given by the equation \(\rho = \frac{m}{V}\). Using the values provided, \(\rho = \frac{320g}{40cm^3} = 8.0 g/cm^3\). The unit for density is derived from the units of mass and volume used.
(c)(i)
For the correct answer:
friction / drag (upward arrow)
weight (downward arrow)
As an object falls through a fluid like water, it experiences two main vertical forces. The downward force is its weight, caused by gravity. The upward force opposing the motion is the frictional force, also known as drag or water resistance in this context.
(c)(ii)
For the correct answer:
(falling with) {constant / steady / uniform} speed
When the upward force of drag becomes equal in size to the downward force of weight, the resultant force on the object is zero. According to Newton’s laws of motion, an object with no resultant force acting on it will not accelerate, so it continues to fall at a constant speed, known as its terminal velocity.
