<span>Answer:
Using 1/f = 1/d' + 1/d ...(where d' object distance and d is image distance)
1/4 = 1/7 + 1/d
1/4 - 1/7 = 1/d
3/28 = 1/d
d = 28/3
d = 9.33 cm</span>
Answer:
B. An Iron Bar place in a room becomes cooler than its surroundings.
Answer with Explanation:
We are given that
Weight of an ore sample=17.5 N
Tension in the cord=11.2 N
We have to find the total volume and the density of the sample.
We know that
Tension, T=
=buoyancy force
T=Tension force
W=Weight
By using the formula

N

Where
=Volume of object
=Density of water
=Acceleration due to gravity
Substitute the values then we get


Volume of sample=
Density of sample,
Where mass of ore sample=1.79 kg
Substitute the values then, we get

Density of the sample=
The question is somewhat ambiguous.
-- It's hard to tell whether it's asking about '3 cubic meters'
or (3m)³ which is actually 27 cubic meters.
-- It's hard to tell whether it's asking about '100 cubic feet'
or (100 ft)³ which is actually 1 million cubic feet.
I'm going to make an assumption, and then proceed to
answer the question that I have invented.
I'm going to assume that the question is referring to
'three cubic meters' and 'one hundred cubic feet' .
OK. We'll obviously need to convert some units here.
I've decided to convert the meters into feet.
For 1 meter, I always use 3.28084 feet.
Then (1 meter)³ = 1 cubic meter = (3.28084 ft)³ = 35.31 cubic feet.
So 3 cubic meters = (3 x 35.31 cubic feet) = 105.9 cubic feet.
That's more volume than 100 cubic feet.