Explanation:
Work done is given by the product of force and displacement.
Case 1,
1. A boy lifts a 2-newton box 0.8 meters.
W = 2 N × 0.8 m = 1.6 J
2. A boy lifts a 5-newton box 0.8 meters.
W = 5 N × 0.8 m = 4 J
3. A boy lifts a 8-newton box 0.2 meters.
W = 8 N × 0.2 m = 1.6 J
4. A boy lifts a 10-newton box 0.2 meters.
W = 10 N × 0.2 m = 2 J
Out of the four options, in option (2) ''A boy lifts a 5-newton box 0.8 meters'', the work done is 4 J. Hence, the greatest work done is 4 J.
Explanation:
a) Density is the amount of mass in a specific amount of volume
b) Some substances are less dense than water so will float and vice versa
c) The wooden plank has less density than water due to having larger volume and vice versa with the wooden block since volume and density are inversely proportional
II) (a) They are all metals
(b) water -> Compound
oxygen -> Element
Gold-> Element
Salt-> Compound
The equivalent resistance of resistors connected in parallel is
In our problem, we have 5 identical resistor of resistance
, so their equivalent resistance is
The problem also says that the equivalent resistance is
, so we can find the resistance R of each piece of wire:
In the initial wire, it's like the 5 pieces are connected in series, so the equivalent resistance of the wire is just the sum of the resistances of the 5 pieces: