Answer:
c. 1600J
Explanation:
The loss in potential energy of the boy is given by:
where
m = 40 kg is the mass of the boy
g = 9.8 m/s^2 is the acceleration of gravity
is the total change in the height of the boy (4 metres + 2 cm due to the compression of the spring)
Substituting, we find
F = ma
We have mass = 20kg
And we need to solve for acceleration
So acceleration is change in velocity over time, in this case we have one velocity and we can assume the man started from rest so
12.3 / 0.9 = a
a = 13.6667
Now we can plug that into F = ma
F = (20)(13.6667)
F = 273.334
Rounding
F = 273.33
Now he is traveling east so we need a force towards the rest, or in the opposite direction to stop his motion.
If we assume east is the positive direction then we need a force of
-273.33 N to stop the man or 273.33 towards the west.
Answer:
v_f = 10.38 m / s
Explanation:
For this exercise we can use the relationship between work and kinetic energy
W = ΔK
note that the two quantities are scalars
Work is defined by the relation
W = F. Δx
the bold are vectors. The displacement is
Δx = r_f -r₀
Δx = (11.6 i - 2j) - (4.4 i + 5j)
Δx = (7.2 i - 7 j) m
W = (4 i - 9j). (7.2 i - 7 j)
remember that the dot product
i.i = j.j = 1
i.j = 0
W = 4 7.2 + 9 7
W = 91.8 J
the initial kinetic energy is
Ko = ½ m vo²
Ko = ½ 2.0 4.0²
Ko = 16 J
we substitute in the initial equation
W = K_f - K₀
K_f = W + K₀
½ m v_f² = W + K₀
v_f² = 2 / m (W + K₀)
v_f² = 2/2 (91.8 + 16)
v_f = √107.8
v_f = 10.38 m / s
Answer: Pressure fluctuations travel along the direction of propagation of the sound wave.
Explanation:
Sound wave is a type of longitudinal wave. It is defined as a wave which consist of vibrations of particles traveling through a medium( such as air, or water).
Sound wave is propagated by the alternating adiabatic compression and expansion of the medium. The COMPRESSIONS are regions of high air pressure while the RAREFACTIONS are regions of low air pressure. Therefore, Since a sound wave consists of a repeating pattern of high-pressure and low-pressure regions moving through a medium, it is sometimes referred to as a PRESSURE WAVE.
The direction of the vibrating particles is parallel to the direction of propagation and that's why it's a type of LONGITUDINAL WAVE. Therefore, the correct option that
concludes about the direction in which such pressure fluctuations travel is
(Pressure fluctuations travel along the direction of propagation of the sound wave.)
The density of a substance is the ratio of its mass to its volume. So whatever volume you have (call it 
), the density 
is computed by
