Answer:
(a) t = 1.67 s
(b) s₂ = 45 m
Explanation:
Here, we use the formula:
s = vt
FOR Seth:
s₁ = v₁t₁
where,
s₁ = distance covered by Seth
v₁ = speed of Seth = 9 m/s
t₁ = time taken by Seth
FOR Mack:
s₂ = v₂t₂
where,
s₂ = distance covered by Mack
v₂ = speed of Mack = 27 m/s
t₂ = time taken by Mack
since, initially Mack is 30 m behind Seth. Therefore,
(a)
s₂ = s₁ + 30 m
using formulae:
v₂t₂ = v₁t₁ + 30 m
but, the time of catching is same for both (t₁ = t₂ = t)
v₂t = v₁t + 30 m
using values:
(27 m/s)t - (9 m/s)t = 30 m
t = (30 m)/(18 m/s)
<u>t = 1.67 s</u>
(b)
s₂ = v₂t
using values:
s₂ = (27 m/s)(1.67 s)
<u>s₂ = 45 m</u>
When the temperature increases, the intermolecular forces between the molecules of a liquid become weaker, and some bonds break easily. Thus as temperature increases, the surface tension of a liquid decreases.
Answer:
hydrogen bridge
Explanation:
Joule's relationship to heat and temperature is true for all materials where we assume that interatomic forces are linear, when atoms separate these forces decrease. There is a point where the separation between atoms is enough that thermal agitation can separate the molecules and there is a change of state, generally from solid to liquid and from liquid to vapor. When these changes of state are occurring all the energy supplied is used to break the links, so the temperature does not change.
In the specific case of water, there is a bond called a hydrogen bridge that breaks around 4ºC, therefore, at this temperature there is a deviation from the curve since this link is being broken, this does not lead to a change of macroscopic state.
For the other temperatures the water behaves like the other bodies.
Answer: The correct answer is True.
Explanation:
Loudness of sound is referred to how soft or loud a sound is for the listener.
This term is measured in a unit known as decibels referred to as dB.
This unit is used to measure the relative intensity of sounds on a scale from zero to 100 dB.
More the value of decibels, it will be uncomfortable for a person to hear that sound.
So Yes, the loudness of sound is measured in decibels.
Answer:
Where the electric potential is constant, the strength of the electric field is zero.
Explanation:
As a test charge moves in a given direction, the rate of change of the electric potential of the charge gives the potential gradient whose negative value is the same as the value of the electric field. In other words, the negative of the slope or gradient of electric potential (V) in a direction, say x, gives the electric field (Eₓ) in that direction. i.e
Eₓ = - dV / dx ----------(i)
From equation (i) above, if electric potential (V) is constant, then the differential (which is the electric field) gives zero.
<em>Therefore, a constant electric potential means that electric field is zero.</em>
