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To solve this problem it is necessary to apply the concepts of Work. Work is understood as the force applied to travel a determined distance, in this case the height. The force in turn can be expressed by Newton's second law as the ratio between mass and gravity, as well

Where,
m = mass
h = height
g = Gravitational constant
When it ascends to the second floor it has traveled the energy necessary to climb a height, under this logic, until the 4 floor has traveled 3 times the height h of each of the floors therefore

Replacing in our equation we have to

The correct answer is 4.
3.4m/s
Explanation:
Given parameters:
Distance to school = 14.4km
Time taken by Amy = 49min
Time taken by bill = 20min after Amy = 20+49 = 69min
Unknown parameters:
How much faster is Amy's average speed = ?
Solution:
Average speed is the rate of change of total distance with total time taken.
Average speed = 
convert units to meters and seconds
1000m = 1km
60s = 1min
Distance to school = 14.4 x 1000 = 14400m
Time taken by Amy = 49 x 60 = 2940s
Time taken by Bill = 69 x 60 = 4140s
Average speed of Amy =
= 4.9m/s
Average speed of Bill =
= 1.4m/s
Differences in speed = 4.9 - 1.5 = 3.4m/s
Amy was 3.4m/s faster than Bill
learn more:
Average speed brainly.com/question/8893949
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Answer:
1.785 m/s
Explanation:
The momentum can be calculated using the expression below
M1 *V1 + M2 * V2 = (M1+M2) V3
M1= mass of van=9000 kg
M2= mass of car= 850kg
V3= velocity of entangled car
V1= Velocity of the van= 0
V2= velocity of the car= 5 m/ s
Substitute the values
(900×0) + (500×5)=( 900+500)× V3
2500=1400 V3
V3=2500/1400
V3= 1.785 m/s
Hence, velocity of the entangled cars after collision is 1.785 m/s