bus via
4. Solve the following word problems. Each question carries 4 marks.
(8 marks)
a) A 56.8 kg concrete slab can be balanced by two concrete pillars, each weighing
41.3 kg. How many concrete pillars are needed to support slabs that weigh 681.6
kg? Calculate the total weight of the slabs and the pillars.
b) In the past, Pintu and Amu could finish running a race in 29.8 seconds and
28 seconds, respectively. At present, they can finish the race in 255 seconds and
31.5 seconds, respectively. Compare their present timing with their previous timing.
Who improved in their timing and by how much?
Answers
Answer:
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Step-by-step explanation:
uestion
Why does chopping an onion make you cry?
Answer
Unstable chemicals.
Camp Kearny, Cal. “Anti-onion” gas mask. Between 1917-1919. Prints & Photographs Division, Library of Congress.
Onions produce the chemical irritant known as syn-propanethial-S-oxide. It stimulates the eyes’ lachrymal glands so they release tears. Scientists used to blame the enzyme allinase for the instability of substances in a cut onion. Recent studies from Japan, however, proved that lachrymatory-factor synthase, (a previously undiscovered enzyme) is the culprit (Imani et al, 2002).
Maule’s seed catalogue for 1891 by Wm. Henry Maule (Firm). Henry G. Gilbert Nursery and Seed Trade Catalog Collection (on the Internet Archive), National Agricultural Library.
The process goes as follows:
Lachrymatory-factor synthase is released into the air when we cut an onion.
The synthase enzyme converts the amino acids sulfoxides of the onion into sulfenic acid.
The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. The lachrymal glands become irritated and produces the tears