<span>This pivot is called refraction. It happens because different materials have different densities. The more dense the material the more atoms the light collides with and the slower it travels; the less dense, the fewer the collisions and hence a faster velocity. This pivoting, or refraction, is caused by the light either slowing down or speeding up.</span>
Answer:
The distance the bungee cord that would be stretched 0.602 m, should be selected when pulled by a force of 380 N.
Explanation:
As from the given data
the length of the rope is given as l=30 m
the stretched length is given as l'=41m
the stretched length required is give as y=l'-l=41-30=11m
the mass is m=95 kg
the force is F=380 N
the gravitational acceleration is g=9.8 m/s2
The equation of k is given by equating the energy at the equilibrium point which is given as

Here
m=95 kg, g=9.8 m/s2, h=41 m, y=11 m so

Now the force is
or

So here F=380 N, k=630.92 N/m

So the distance is 0.602 m
Answer:
the work done by the lawnmower is 236.14 J.
Explanation:
Given;
power exerted by the lawnmower engine, P = 19 hp
time in which the power was exerted, t = 1 minute = 60 s.
1 hp = 745.7 watts
The work done by the lawnmower is calculated as follows;

Therefore, the work done by the lawnmower is 236.14 J.
<span>Every 10s 5 waves; t1 = 2s for each wave
When v = 1.5m/s, 3 waves in 10s t2 = 10 / 3s
Calculating the frequency in first case f1 = 5 / 10 = 0.5
Calculating the frequency in second case f2 = 3 / 10 = 0.3
Using the Doppler formula f = (1-v/c) f0
For the formula f = f2, v = velocity of boat= 1.5 m/s, f0 = f1, c is velocity of wave
0.3 = 0.5 x (1 - 1.5/c) => 1.5/c = 1 - 0.6 => 1.5/c = 0.4 => c = 1.5/0.4
Velocity of the wave = 3.75 m/s</span>
Refer to the diagram shown below.
The force, F, is applied at 5 cm from the elbow.
For dynamic equilibrium, the sum of moments about the elbow is zero.
Take moments about the elbow.
(5 cm)*(F N) - (30 cm)*(250 N) = 0
F = (30*250)/5 = 1500 N
Answer: 1500 N