The only vertical forces are weight and normal force, and they balance since the surface is horizontal. The horizontal forces are the applied force (uppercase F) in the direction the block slides and the frictional force (lowercase f) in the opposite direction.

Apply Newton's 2nd Law in the horizontal direction:
ΣF = ma
F - f = ma
where f = µmg

F - µmg = ma
F = m(a +µg)
F = (20 kg)(1.4 m/s² + 0.28(9.8 m/s²)

F = 83 N

3 0

2 years ago

This list shows the heights in feet of the 30 tallest mountains in the United States. 14,269 14,361 14,470 14,831 16,237 14,270

antoniya [11.8K]

Answer: a. Frequency. 20, 4, 3, 1, 1, 0, 1

Explanation:

Interval(Height in feet) - - - - - - - - frequency

14000 - 14999 - - - - - - - - - - - - - - - 20

15000 - 15999 - - - - - - - - - - - - - - - 4

16000 - 16999 - - - - - - - - - - - - - - - 3

17000 - 17999 - - - - - - - - - - - - - - - 1

18000 - 18999 - - - - - - - - - - - - - - - 1

19000 - 19999 - - - - - - - - - - - - - - - 0

20000 - 20999 - - - - - - - - - - - - - - 1

Frequency : (20, 4, 3 1, 1, 0, 1)

8 0

2 years ago