The layer of Earth that we live on
1 answer:
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Answer:
Explanation:
They traveled this distance in 2 parts, essentially. Part 1 had an average speed for a certain number of hours, part 2 had an average speed for a certain number of hours, and those 2 parts taken together took them a distance of 364 km. In equation form, that looks like this:
km/hr part 1 + km/hr part 2 = 364 km
Now we need to find each part on the left side of that equation. Part 1 first:
We traveled 65 km/hr for 2 hours, so that took us
and canceling out the hour label, we have that in part 1 we got
65(2) = 130 km. Good. Now onto the second part, where our unknown is.
We traveled 78 km/hr the second part for x hours, so that took us
and canceling out the hour label, we have that in part 2 we got
78x km. Now we can fill in the main equation (the one in bold print)
130 km + 78x km = 364 km and subtracting 130 km from both sides:
78x km = 234 km and dividing by 78 km:
x = 3 hours. Part 2 took 3 hours. Part 1 took 2 hours, so the whole trip took 5 hours.
The final combined velocity after the collision is 20.2 m/s
Explanation:
We can solve this problem by using the law of conservation of momentum: in fact, in absence of external forces, the total momentum of the two car and of the truck must be conserved before and after the collision.
This means that we can write the following equation:
where:
is the mass of the sport car
is the initial velocity of the car (taking its direction as positive direction)
is the mass of the truck
is the initial velocity of the truck
is the final combined velocity of the car and the truck, after the collision
Re-arranging the equation and substituting the values, we find the velocity after the collision:
And the positive sign indicates their final direction is the same as the initial direction of the two vehicles.
Learn more about momentum here:
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