<u>Answer:</u>
<em>A water strider can walk along the surface of earth due to the surface tension of water.
</em>
<u>Explanation:</u>
Fluids have a <em>tendency to shrink to minimum possible surface area</em> and this is called surface tension. It usually occurs due to the greater force of cohesion between molecules of same substance when compared to adhesive force between molecules of different substances. Objects with greater densities can float along water surface due to the <em>role played by surface tension.
</em>
When insects walk along the water surface they are pulled down due to gravity. But the force of attraction between the legs of the insect and water molecules is minimal. Thus the surface tension would always tend to maintain the <em>flatness of water overcoming</em> the push by the legs of the strider.
When the insect’s weight pulls it down , the surface tension pushes it upwards overcoming this force of gravity. This is how<em> water striders move along the surface of water. </em>
Answer: µ=0.205
Explanation:
The horizontal forces acting on the ladder are the friction(f) at the floor and the normal force (Fw) at the wall. For horizontal equilibrium,
f=Fw
The sum of the moments about the base of the ladder Is 0
ΣM = 0 = Fw*L*sin74.3º - (25.8kg*(L/2) + 67.08kg*0.82L)*cos74.3º*9.8m/s²
Note that it doesn't matter WHAT the length of the ladder is -- it cancels.
Solve this for Fw.
0= 0.9637FwL - (67.91L)2.652
Fw=180.1/0.9637
Fw=186.87N
f=186.81N
Since Fw=f
We know Fw, so we know f.
But f = µ*Fn
where Fn is the normal force at the floor --
Fn = (25.8 + 67.08)kg * 9.8m/s² =
910.22N
so
µ = f / Fn
186.81/910.22
µ= 0.205
Answer:
Explanation:
Mass of nails is 0.25kg
Mass of hammer 5.2kg
Speed of hammer is =52m/s
Then, Ben kinetic energy is given as
K.E= ½mv²
K.E= ½×5.2×52²
K.E= 7030.4J
Given that, two-fifth of kinetic energy is converted to internal energy
Internal energy (I.E) = 2/5 × K.E
Internal energy (I.E) = 2/5 × 7030.4
I.E=2812.16J.
Energy increase is total Kinetic energy - the internal energy
∆Et= K.E-I.E
∆Et= 7030.4 - 2812.16
∆Et= 4218.24J
Question:
1) The universe is cooling which, according to the Big Bang Theory, is expected to happen as the cosmos accumulates.
2) The universe is warming which, according to the Big Bang Theory, is expected to happen as the cosmos disperses.
3) The universe is cooling which, according to the Big Bang Theory, is expected to happen as the cosmos disperses.
4) The universe is warming which, according to the Big Bang Theory, is expected to happen as the cosmos accumulates.
Answer:
The correct option is;
3) The Universe is cooling which, according to the Big Bang Theory, is expected to happen as the cosmos disperses
Explanation:
With the temperature measurement carried out using the CSIRO radio telescope, Astronomers have been able to determine a temperature difference in the universe from 5.08 Kelvin 7.2 billion light years away to 2.73 Kelvin in the Universe today, which is in support of the Big Bang theory that as the Universe expanded from a state of extreme temperature that cools down as the Universe expands or the cosmos disperses.
Answer:
The value of third charge is 0.8μC.
Explanation:
Given that.
Magnitude of net force=4.444 N
According to figure,
Suppose, First charge = 2.4 μC
Second charge = 6.2 μC
Distance r₁ = 9.8 cm
Distance r₂ = 2.1 cm
We need to calculate the value of r
Using Pythagorean theorem

Put the value into the formula


We need to calculate the force
Using formula of force

Force F₁₂,



Force F₂₃,

We need to calculate the value of third charge





Hence, The value of third charge is 0.8μC.