Answer:
The family may be addicted to technology by using their cellphones to communicate is still communicating in a way, but it would be better to use social face- to - face interactions.
Explanation:
Answer:

Explanation:
consider the mass of each train car be m
m₁ = m₂ = m₃ = m
speed of the three identical train
u₁ = u₂ = u₃ = 1.8 m/s
m₄ = m u₄ = 4.5 m/s
m₅ = m u₅ = 0 (initial velocity )
final velocity
v₁ = v₂ = v₃ = v₄ = v₅ = v
using conservation of momentum
m₁u₁ + m₂u₂ + m₃u₃ + m₄u₄ + m₅u₅ = m₁v₁ + m₂v₂ + m₃v₃ + m₄v₄ + m₅v₅
m (1.8 + 1.8 + 1.8 +4.5) = 5 m v


Answer:
m≈501.57 g
Explanation:
The density formula is:
d=m/v
Let’s rearrange the formula for m. m is being divided by v. The inverse of division is multiplication, so multiply both aides by v.
d*v= m/v*v
d*v=m
The mass can be found by multiply the density and the volume.
m=d*v
The density is 1.06 grams per milliliter and the volume is 473.176 milliliters.
d= 1.06 g/mL
v= 473.176 mL
Substitute the values into the formula.
m= 1.06 g/mL * 473.176 mL
Multiply. When multiplying, the mL will cancel out.
m= 501.56656 g
Let’s round to the nearest hundredth. The 6 in the thousandth place tells us to round the 6 to a 7 in the hundredth place.
m ≈501.57 g
The mass is about 501.57 grams.
First of all, the formula for speed is;
Speed=distance/time
From the question, you have;
distance=7,200km
Time=9 hours
So that will be;
Speed=7200/9
When divided, you will have;
Speed=800
The unit for speed is km/hr or m/s. So that will be;
Speed=800km/hr
Hope that helped, have a nice day