No additional force is required because it's already going downhill
Answer:
Speed of bike = 2.5 km/h
Distance travel = 1,000 km (Approx.)
Explanation:
Given:
Distance cover by Helmut = 5 km
Time taken = 2 hour
Find:
Speed of bike
Computation:
Speed = Distance / Time
Speed of bike = 5 / 2
Speed of bike = 2.5 km/h
Given:
Speed of plane = 250 km/h
time taken = 3 hr 58 min = 3.967 hr
Find:
Distance travel
Computation:
Distance = Speed x time
Distance travel = 250 x 3.967
Distance travel = 991.669
Distance travel = 1,000 km (Approx.)
Answer:
a) 
b)
º
c) 
Explanation:
From the exercise we know that the collision between Daniel and Rebecca is elastic which means they do not stick together
So, If we analyze the collision we got

To simplify the problem, lets name D for Daniel and R for Rebecca
a) 
Since Daniel's initial velocity is 0



Now, lets analyze the movement in the vertical direction

Since 


Now, we can find the magnitude of Daniel's velocity after de collision

b) To know whats the direction of Daniel's velocity we need to solve the arctan of the angle
º
c) The change in the total kinetic energy is:
ΔK=
ΔK=![\frac{1}{2}[(45kg)(8m/s)^2+(70kg)(7.32m/s)^2-(45kg)(14m/s)^2]=-1094.62J](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7D%5B%2845kg%29%288m%2Fs%29%5E2%2B%2870kg%29%287.32m%2Fs%29%5E2-%2845kg%29%2814m%2Fs%29%5E2%5D%3D-1094.62J)
That means that the kinetic energy decreases