Janetta ran a campaign for student body president, and she really wanted to win. She gave election buttons to everyone and told
1 answer:
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Answer:
Explanation:
Given
Initial speed
distance traveled before coming to rest
using equation of motion
where v=final velocity
u=initial velocity
a=acceleration
s=displacement
for
using same relation we get
divide 1 and 2 we get
So a distance if 213.32 ft is required to stop the vehicle with 80 mph speed
Answer:
D.
Explanation:
In order to know how long after Bill released his rock should Ted throw his if they want the stones to hit the water simultanously, we need to calculate the time needed to hit the water to both rocks independent each other, and just take the difference.
For the rock dropped by Bill, as the only influence on it is gravity (accelerating it downwards with an acceleration equal to g), and v₀ =0, we can use the following kinematic equation:
where y = height = 40 ft.
As all the parameters are given in SI units, it is advisable to convert this value to m, as follows:
Now, we can solve for t, as follows:
For the rock thrown down at 10 m/s, the kinematic equation we just have used becomes:
This leaves us a quadratic equation on t, as follows:
Taking the positive root, we have:
t = -1.02 s + 1.88 s = 0.86 s
So, in order to get that both rocks hit the water at the same time, Ted will need to wait the difference between both times:
Δt = 0.86 s - 1.58s = -0.72 s