Average speed= total distance/total time =12km/h
Answer:
Intensity, 
Explanation:
Power of the light bulb, P = 40 W
Distance from screen, r = 1.7 m
Let I is the intensity of light incident on the screen. The power acting per unit area is called the intensity of the light. Its formula is given by :




So, the intensity of light is
.
To solve this problem we will apply the concept of wavelength, which warns that this is equivalent to the relationship between the speed of the air (in this case in through the air) and the frequency of that wave. The air is in standard conditions so we have the relation,
Frequency 
Speed of sound in air 
The definition of wavelength is,

Here,
v = Velocity
f = Frequency
Replacing,


Therefore the wavelength of that tone in air at standard conditions is 0.589m
Answer:
h = 4271.43 m
Explanation:
given,
Volume of the water = 1 m³
temperature decrease by = 10°C
heat removed from water
Q = m c ΔT
Q = ρ V c ΔT
= 1000 × 1 × 4186 × 10
= 4.186 × 10⁷ J
energy is used to do work to move the water against its weight
Q = force × displacement
4.186 × 10⁷ J = m g × h
4.186 × 10⁷ J = 1000 × 1 × 9.8 × h
h = 4271.43 m
hence, the change in height of is equal to h = 4271.43 m
Answer:
1.6 x
N
Explanation:
If the force between two actual wires has this value, the current is defined to be exactly 1 A.
The force between two parallel wires carrying current can be defined as,
F= μ
L/ 2πd
where,
current
= 1Amp
current
= 2amp
Length 'L'= 1m
distance 'd'= 2.5m
permeability of free space 'μ'= 4πx
N/m
Putting the above values in the equation,
F=( 4πx
x 1 x 2 x 1 )/ 2πx2.5
F= 1.6 x
N