1.1 Basic physics

Question 1

What are the 7 SI quantities and their units?

Answer 1

• Mass (kg)
• Length (m)
• Time (s)
• Current (A)
• Temperature (K)
• Amount of substance (mol)
• Luminosity (cd)

Question 2

Define homogenous

Answer 2

An equation where the units of the left and right hand sides are the same

Question 3

What equation links mass, volume, and density?

Answer 3

Density = mass / volume

Question 4

What is the principle of moments?

Answer 4

For a body to be in equilibrium under the action of a number of forces, the resultant moment about any point is zero

Question 5

Define a moment

Answer 5

The moment of a force about a point is the product of the force and the perpendicular distance from the point to the line of action of the force

Question 6

Define center of gravity

Answer 6

The center of gravity of a body is the point at which its weight can be considered to act

Question 7

What are the two conditions for an object to be in equilibrium?

Answer 7

• The resultant force on the object is zero
• The resultant moment about any point on the object is zero