I should think that Yolanda should use litmus paper throughout the reaction as its color will tell when the mixture is neutral and therefore then, when she can stop adding either the hydrochloric acid or the sodium hydroxide or if one or the other needs to be added to make the solution approach neutral. Blue litmus paper stays blue in a neutral solution, but will turn red in an acidic solution.
D determined by its temperature
Answer:
The speed of the block is 8.2 m/s
Explanation:
Given;
mass of block, m = 2.1 kg
height above the top of the spring, h = 5.5 m
First, we determine the spring constant based on the principle of conservation of potential energy
¹/₂Kx² = mg(h +x)
¹/₂K(0.25)² = 2.1 x 9.8(5.5 +0.25)
0.03125K = 118.335
K = 118.335 / 0.03125
K = 3786.72 N/m
Total energy stored in the block at rest is only potential energy given as:
E = U = mgh
U = 2.1 x 9.8 x 5.5 = 113.19 J
Work done in compressing the spring to 15.0 cm:
W = ¹/₂Kx² = ¹/₂ (3786.72)(0.15)² = 42.6 J
This is equal to elastic potential energy stored in the spring,
Then, kinetic energy of the spring is given as:
K.E = E - W
K.E = 113.19 J - 42.6 J
K.E = 70.59 J
To determine the speed of the block due to this energy:
KE = ¹/₂mv²
70.59 = ¹/₂ x 2.1 x v²
70.59 = 1.05v²
v² = 70.59 / 1.05
v² = 67.229
v = √67.229
v = 8.2 m/s
Answer:
897
Explanation:
Speed of the car, v = 126 km/h, converting to m/s, we have v = 35 m/s and
Radius of the curve, R = 150 mm = 0.15 m
The centripetal acceleration a(c) is given by the formula = v² / R so that
a(c) = 35² / 0.15
a(c) = 1225 / 0.15
a(c) = 8167 m/s²
The force that causes the acceleration is frictional force = µ m g, where
µ = coefficient of friction
m = the mass of the car and
g = acceleration due to gravity, 9.81
From Newton's law:
µ m g = m a(c) , so that
µ = a(c) / g
µ = 8167 / 9.81
µ = 897
Therefore, the coefficient of static friction must be as big as 897
