I believe that the first one is correct because if you have a ball that Weighs 5 pounds and you push it down a ramp it will hit the end with more force than a ball that weighs 2 pounds
This problem is looking for the minimum value of μs that is
necessary to achieve the record time. To solve this problem:
Assuming the front wheels are off the ground for the entire
¼ mile = 402.3 m, the acceleration a = µs·9.8 m/s².
For a constant acceleration, distance = 402.3
m = 1/2at^2 = 804.6 m / (4.43 s)^2 = a = µs·9.8 m/s^2
µs = 804.6 m / (4.43s)^2 / 9.8 m/s^2 = 4.18
Explanation:
u=54 km/h
54*5/18=15 m/s
v=0m/s
t=?
acceleration=-0.5m/s^2
we know that a=v-u/t
so,
t=v-u/a
t=15-0/0.5
=15/0.5
=30
therefore, the time is 30 second
Hope this answer helps you..
<span>If the swimmer is swimming perpendicular to the current, it will take her 66m / 0.42 m/s = 157.14 seconds to cross the river. At the same time, the current will be taking her downstream at a rate of 0.32 m/s. So, when she reaches the opposite bank, her total downstream distance traveled will have been 0.32*157.14 = 50.28 meters.</span>
