Answer:
They will be 140 miles apart 8 hours after the first boy started the trip or 6 hours after the second boy started the trip.
Explanation:
x = the time that the first boy travels at 14 mph
x - 2 = the time the second boy travels at 14 mph
140 the distance between them
Since one travels north and the other east (their roads are perpendicular) the distance between them can be calculated using Pythagorean Theorem
(14*x)^2 + ((x-2)*14)^2 = 140^2
the solutions of the quadratic equation are
x1 = - 6 is not the solution since x > 0
x2 = 8 h is the solution
Kinetic energy because of the wood plank is just still and not moving it’s potential but since it’s asking which one it doesn’t have it doesn’t have kinetic energy cause it’s not moving
Answer:
The minimum coefficient of friction required is 0.35.
Explanation:
The minimum coefficient of friction required to keep the crate from sliding can be found as follows:


Where:
μ: is the coefficient of friction
m: is the mass of the crate
g: is the gravity
a: is the acceleration of the truck
The acceleration of the truck can be found by using the following equation:


Where:
d: is the distance traveled = 46.1 m
: is the final speed of the truck = 0 (it stops)
: is the initial speed of the truck = 17.9 m/s
If we take the reference system on the crate, the force will be positive since the crate will feel the movement in the positive direction.

Therefore, the minimum coefficient of friction required is 0.35.
I hope it helps you!