71
Units of mass
Textbook: Part 3, lesson 71, pp. 10–12
GoalConvert between all units of mass (g, kg, centner, t); calculate in a convenient unit; use them in equations and problems.
New words
units of mass · massa birliklarinet mass · nettolifting capacity · yuk ko‘tarish quvvaticonverting · aylantirish
Explanation
The chain of mass units: 1 000 g = 1 kg, 100 kg = 1 centner, 10 centners = 1 t. When calculating, change all numbers to the smallest unit and write the result in a convenient unit. “Netto” means net mass without packaging: net = total mass − mass of the package. The greatest mass a lift or crane can raise is its lifting capacity.
Worked examples
5 308 kg = 5 t 308 kg; 31 t 40 kg = 31 040 kg.
2 t 150 kg − 9 centners 70 kg = 2 150 kg − 970 kg = 1 180 kg = 1 t 180 kg.
Class activity
“Can the crane lift it?”: the teacher names a crane’s lifting capacity (say 5 t); groups add the masses of the loads and prove whether the crane can lift them.
Practice
1
12 t 305 kg = ? kg
12305
2
4 t − 1 t 650 kg = ? kg
2350
3
Apples with the crate weigh 25 kg 400 g; the empty crate weighs 2 kg 900 g. What is the net mass of the apples in grams?
22500
4
A lift can carry 400 kg. Three people of 70 kg, 85 kg and 95 kg are in it. How many more 25 kg bags of cement can be added?
6
5
In the equation x × 4 = 1 t 200 kg, how many kilograms is x?
300