Answer: F = 131.7N
Explanation:
You are given the following parameters.
Mass M = 30 kg
Coefficient of static friction μ = 0.5
Ø = 30 degrees
When the person is trying to drag the box with force F, the static frictional force Fs will be acting in the opposite direction.
From the figure attached, resolve all forces into horizontal component and vertical component.
Horizontal component:
Fs - F cosØ = 0
Fs = F cosØ
F cosØ = μN ...... (1)
Vertical component:
N + F SinØ - mg = 0
N = Mg - F SinØ ..... (2)
Substitutes m, g and Ø into the equation 2
N = (30 × 9.8) - F × sin30
N = 294 - 0.5F
Substitute N and coefficient of friction into the equation (1)
F cos30 = 0.5 (294 - 0.5F)
Open the bracket
0.8660F = 147 - 0.25F
Collect the like terms
1.116025F = 147
F = 147/1.116025
F = 131.7 N
Therefore, the minimum force the person needs to have to move the box along the floor is 131.7 N
Answer:
Explanation:
Conservation of momentum
Let's say the first child was headed north
North momentum
75(0) + 20(2) + 15(3sin45) = (75 + 20 + 15)vn
vn = 0.6529 m/s
East momentum
75(0) + 20(0) + 15(3cos45) = (75 + 20 + 15)ve
ve = 0.28927 m/s
θ = arctan(0.28927/0.6529)
θ = 23.896...
θ = 24° east of north
Answer:
Explanation:
Pressure can be defined as the force per unit area hence there is an inverse relationship between pressure exerted by a substance and the area of that substance. For instance,
(1) if a bag of sand if filled with sand and an individual steps on this bag. The feet of he individual will form no shape/displace little sand sideways in the bag. But if the same quantity of sand is poured in a bigger bag (larger area) and the same individual stands on the bag, the feet of the individual will "sink" (decreased pressure from the bag) displacing some sand sideways.
(2) The straps of a bag are made wide (and not slim) so that the bag can exert lesser pressure on the shoulders when the same quantity of load is carried by the bag than if the straps were made narrow/slim.
11. aboard
12. marsh
13. swore
14. starch
15. barge
16.swear
17. coarse
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Answer:
L = 40 cm
Explanation:
A microscope is an optical instrument built by two lenses in such a way that the image of the first is formed within the distance of the other (eyepiece), so that the latter creates an enlarged virtual image of the object, for which the magnification of the microscope is the same to the multiplication of the magnification of each lens
M = - L / f₀ (25 cm /
)
where fo and fe are the focal lengths of the objective and eyepiece, 25 cm is the near vision distance and L is the length of the microscope
L = - M f_{o} f_{e} / 25
let's calculate
L = - (-100) 2 5/25
L = 40 cm
