Answer:
Δ KE = 249158.6 kJ
Explanation:
given data
Truck mass M = 1560 Kg
Truck initial speed, u = 28 m/s
mass of car m = 1070 Kg
initial speed of car u1 = 0 m/s
solution
first we get here final speed by using conservation of momentum that is express as
Mu = (M+m) V .......................1
put here value we get
1560 × 28 = (1560 + 1070 ) V
solve it we get
final speed V = 16.60 m/s
and
Change in kinetic energy will be here
Δ KE =
.................2
put here value and we get
Δ KE =
solve it we get
Δ KE = 249158.6 kJ
Answer:
The force of friction that acts on him is

Explanation:
The firefighter with an acceleration of 3m/s^2 take the gravity acceleration as 10m/s^2 isn't necessary to know the coefficient of friction just to know the force of friction:




Sole to Fk



Take into account that in a standing wave, the frequency f of the points executing simple harmonic motion, is simply a multiple of the fundamental harmonic fo, that is:
f = n·fo
where n is an integer and fo is the first harmonic or fundamental.
fo is given by the length L of a string, in the following way:
fo = v/λ = v/(L/2) = 2v/L
becasue in the fundamental harmonic, the length of th string coincides with one hal of the wavelength of the wave.