Answer:
Work Done = W
force = F
Distance = d
W = Fd
or W = F*d
W (in joules) = 3.5*4 = 14 Nm (or J)
1Nm = 1J
so newton meters and joules are the same
Power = Work (in joules) /time (in seconds)
i don’t know the time so i can’t solve it
Answer:
Nora's boat is moving towards Sam at 5 km/hr
Explanation:
The question says that Nora is few meters behind Nancy and is still with respect to her that means the relative velocity between Nora and Nancy is zero
Vrel = 5 - Vnora= 0 ⇒ Vnora = 5km/hr
Pictorially we can represent the given condition as:
Nora-------few meters------Nancy ----------------- Sam
5km/hr 5km/hr →
Hence, Nora's boat is moving towards Sam at 5km/hr.
Answer:
Wave A.
Explanation:
The energy of a wave is directly proportional to the square of the amplitude.
If a wave has higher amplitude, it will have more energy. On the other hand, a wave having lower amplitude, it will have less eenergy.
In this case, we need to tell which wave has higher energy. Hence, the correct option is A because it has a higher amplitude.
The boat is moving at 22 m/s while the man is moving at 23.1 m/s.
That means the man, relative to the boat, is moving at 23.1-22 = 1.1 m/s.
v =d/t, so t = d/v --> t = 3/1.1 = 2.7 s
is the intensity of the sound.
Answer: Option B
<u>Explanation:</u>
The range of sound intensity that people can recognize is so large (including 13 magnitude levels). The intensity of the weakest audible noise is called the hearing threshold. (intensity about
). Because it is difficult to imagine numbers in such a large range, it is advisable to use a scale from 0 to 100.
This is the goal of the decibel scale (dB). Because logarithm has the property of recording a large number and returning a small number, the dB scale is based on a logarithmic scale. The scale is defined so that the hearing threshold has intensity level of sound as 0.

Where,
I = Intensity of the sound produced
= Standard Intensity of sound of 60 decibels = 
So for 19 decibels, determine I as follows,



When log goes to other side, express in 10 to the power of that side value,

