6 is the answer I remember the answer from when I took this and it was easy
Answer:B
Explanation:sorry they removed my answer for some reason.
Answer:
Speed of the ball relative to the boys: 25 km/h
Speed of the ball relative to a stationary observer: 35 km/h
Explanation:
The RV is travelling at a velocity of

Here we have taken the direction of motion of the RV as positive direction.
The boy sitting near the driver throws the ball back with speed of 25 km/h, so the velocity of the ball in the reference frame of the RV is

with negative sign since it is travelling in the opposite direction relative to the RV. Therefore, this is the velocity measured by every observer in the reference frame of the RV: so the speed measured by the boys is
v = 25 km/h
Instead, a stationary observer outside the RV measures a velocity of the ball given by the algebraic sum of the two velocities:
v = +60 km/h + (-25 km/h) = +35 km/h
So, he/she measures a speed of 35 km/h.
Answer:
α= 1.3 10-5 ºC⁻¹
Explanation:
La dilatación termica de los cuerpos esta dada por la relación
ΔL = L₀ α ( T -T₀)
en este caso nos piden el coeficiente de dilatación térmica
α =DL/L₀ DT
calculemos
α = ( 100,13 -100)/[100 (100 – 0)]
α = 1,3 10-5 ºC⁻¹
Traduction
The thermal expansion of bodies is given by the relationship
ΔL = L₀ α (T -T₀)
in this case they ask us for the coefficient of thermal expansion
α = ΔL / L₀ ΔT
let's calculate
α = (100,13 -100) / [100 (100 - 0)]
α= 1.3 10-5 ºC⁻¹