Answer:
10.5min
Explanation:
Given parameters:
Distance = 4200m
Speed = 400m/min
Unknown:
Time taken for this run = ?
Solution:
Speed is the distance divided by the time taken.
Speed = 
Time = 
Now insert the parameters and solve;
Time = 
= 10.5min
F = 2820.1 N
Explanation:
Let the (+)x-axis be up along the slope. The component of the weight of the crate along the slope is -mgsin15° (pointing down the slope). The force that keeps the crate from sliding is F. Therefore, we can write Newton's 2nd law along the x-axis as
Fnet = ma = 0 (a = 0 no sliding)
= F - mgsin15°
= 0
or
F = mgsin15°
= (120 kg)(9.8 m/s^2)sin15°
= 2820.1 N
The correct answer is B. hopes this help
The best object to show the Earth's true appearance is something round and smooth. Since the earth is only slightly oblate, it doesn't matter based on its size, and you would use a pool ball as the perfect scale model, because it is very round and smooth.
