Answer:
Explanation:
Work is defined as the scalar product of force and distance
W=F•d
Given that
F = 8.5i + -8.5j. +×-=-
F=8.5i-8.5j
d = 2.5i + cj
If the work in the practice is zero, then W=0
therefore,
W=F•ds
0=F•ds
0=(8.5i -8.5j)•(2.5i + cj)
Note that
i.i=j.j=k.k=1
i.j=j.i=k.i=i.k=j.k=k.j=0
So applying this
0=(8.5i -8.5j)•(2.5i + cj)
0= (8.5×2.5i.i + 8.5×ci.j -8.5×2.5j.i-8.5×cj.j)
0=21.25-8.5c
Therefore,
8.5c=21.25
c=21.25/8.5
c=2.5
Answer:
F = 294.3 [N]
Explanation:
To solve this problem we must use Newton's second law which tells us that force is equal to the product of mass by acceleration. It is this particular case the acceleration is due to the gravitational acceleration since the body is in free fall.
Therefore we have:
F = m*g
where:
F = force [N]
m = mass = 30 [kg]
g = gravity acceleration = 9.81 [m/s^2]
F = 30*9.81
F = 294.3 [N]
Answer:
540C.
Explanation:
A capacitor of capacitance C when charged to a voltage of V will have a charge Q given as follows;
Q = CV ----------(i)
From the question, the initial charge on the capacitor is the charge on it before it was connected to the resistor. In other words, the initial charge on the capacitor will have a maximum value which can be calculated using equation (i) above.
Where;
C = 6F
V = 90V
Substitute these values into equation (i) as follows;
Q = 6 x 90
Q = 540 C
Therefore, the initial charge on the capacitor is 540C.
Answer:
Explanation:
In a frictionless system with no acceleration, the tension in the rope must be F along its entire length
FBD analysis of the lower pulley has two upward acting tension vectors F and one downward acting weight vector W
2F = W
F = W/2
FBD analysis of the upper pulley has one upward acting support vector T and three downward acting tension vectors F
T = 3F
T = 3(W/2)
T = 1.5W