Skeleton and muscles:
3.
Weight
lifted and force
needed calculations based on the action of muscles e.g. antagonistic
muscles of elbow joint
Doc Brown's Biology exam study revision notes
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INDEX
of biology notes on the skeleton and muscles
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(3) Weight lifted and force
calculations based on the action of muscles
Some
example questions (answers)
ALL based on the diagram
above for the antagonistic biceps and triceps muscles of the elbow
joint
Assume the gravitational field constant is
10 N/kg Question 1
If d1 = 0.40 m, d2 = 5 cm, using the above diagram for help, and applying the principle of moments, calculate the minimum force needed by the biceps contraction to lift a weight of 20 N.
Question 2
If d1 = 0.36 m, d2 = 0.06 m, using the above diagram for help, and applying the principle of moments, calculate the minimum force needed by the biceps contraction to lift a
mass of 3 kg.
Question 3
If d1 = 45 cm, d2 = 5 cm, using the above diagram for help, and applying the principle of moments, calculate the minimum force needed by the biceps contraction to lift a weight of 15 N.
Question 4
If d1 = 48 cm, d2 = 6 cm, using the above
diagram for help, and applying the principle of moments,
calculate the minimum force needed by the biceps contraction to
lift a weight of 2 kg.
Question 5
If d1 = 0.50 m, d2 = 0.05 m, using the above diagram for help, and applying the principle of moments, if the maximum strength of a person's biceps muscle contraction creates a force of 150 N, calculate the maximum weight the person's arm can raise
and hold.
Question 6
If d1 = 0.60 m, d2 = 0.06 m, using the above diagram for help, and applying the principle of moments, if the maximum strength of a person's biceps muscle contraction creates a force of 180 N, calculate the maximum
mass the person's arm can raise
and hold.
Question 7
If d1 = 0.50 m, d2 = 0.05 m, using the above diagram for help, and applying the principle of moments, if the maximum strength of a person's biceps muscle contraction creates a force of 200 N, calculate the maximum weight the person's arm can raise
and hold.
Question 8
If d1 = 0.40 m, d2 = 0.06 m, using the above diagram for help, and applying the principle of moments, if the maximum strength of a person's biceps muscle contraction creates a force of 240 N, calculate the maximum
mass the person's arm can raise
and hold.
(Answers)
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Answers to the muscle
force questions using the principle of moments
Remember 1 kg mass is equivalent to 10 N on the
Earth's surface.
Q1 F1 x d1 = F2 x d2, convert cm to m, 20
x 0.40 = F2 x 0.05, F2 = 20 x 0.40 / 0.05 =
160 N
Q2 3 kg = 3 x 10 = 30 N, F1 x d1 = F2 x d2, convert cm to m, 30
x 0.36 = F2 x 0.06 x F2, F2 = 30 x 0.36 / 0.06 =
180 N
Q3 F1 x d1 = F2 x d2, convert cm to m, 15
x 0.45 = F2 x 0.05, F2 = 15 x 0.45 / 0.05 =
135 N
Q4 2 kg = 2 x 10 = 20 N, F1 x d1 = F2 x d2, convert cm to m, 20
x 0.48 = F2 x 0.06, F2 = 20 x 0.48 / 0.06 =
160 N
Q5 F1 x d1 = F2 x d2, F1 x 0.50 = 150 x
0.05, F1 = 150 x 0.05 / 0.50 =
15 N
Q6 F1 x d1 = F2 x d2, F1 x 0.60 = 180 x
0.06, F1 = 180 x 0.06 / 0.60 = 18 N, mass = 18 / 10 =
1.8 kg
Q7 F1 x d1 = F2 x d2, F1 x 0.50 = 200 x
0.05, F1 = 200 x 0.05 / 0.50 =
20 N
Q8 F1 x d1 = F2 x d2, F1 x 0.40 = 240 x
0.06, F1 = 240 x 0.06 / 0.40 = 36 N, mass = 36 /10 =
3.6 kg
