Which appliance uses more energy?

-- the CD player . . . . .  3,924,000 joules

-- the blender . . . . .  36,000 joules

-- the hair dryer . . . . .  270,000 joules

-- the computer . . . . .  7,200,000 joules

The computer is the big loser, mainly because it was left turned on for so long.

The computer uses more energy.

Explanation:

We know that the power of an electrical appliance is given by :

E is the energy of the appliance

t is the time taken

For CD player :

Power = 30 watts

Time, t = 3 hours = 10800 s

E = 324000 Joules

or E = 324 kJ

For blender :

Power = 300 watts

Time, t = 2 hours = 120 s

E = 36000 Joules

or E = 36 kJ

For hair dryer:

Power = 1500 watts

Time, t = 3 minutes = 180 s

E = 270000 Joules

or E = 270 kJ

For computer:

Power = 200 watts

Time, t = 10 hours= 36000 s

E = 7200000 Joules

or E = 7200 kJ

So, the computer uses more energy i.e. 7200 kJ. Hence, the correct option is (d).

a longitudinal wave moves energy that is to the direction of the wave’s movement. - true

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.