Here's the information given for the non-uniform ladder:
Length of ladder L=8.0 m
Mass of ladder m=10.0 kg
Center of gravity (CG) from the bottom B: dCG=2.0 m
Angle with the vertical wall: α=30∘. This means the angle with the horizontal ground is θ=90∘−30∘=60∘.
Upper end (A) against a smooth wall (no friction).
Lower end (B) on rough ground (friction present).
Acceleration due to gravity g=9.81m/s2.
a) Draw a free body diagram of the ladder.
Imagine the ladder AB leaning against a vertical wall with its base on horizontal ground.
Draw the ladder inclined at 60∘ to the horizontal. Label the top end A and the bottom end B.
Weight (W): A vertical arrow pointing downwards from the center of gravity G. G is located 2.0 m from B along the ladder. The magnitude is W=mg.
Normal force at the wall (NA): A horizontal arrow pointing away from the wall (to the right), acting at point A. Since the wall is smooth, there is no friction here.
Normal force at the ground (NB): A vertical arrow pointing upwards, acting at point B.
Frictional force at the ground (Ff): A horizontal arrow pointing towards the wall (to the left), acting at point B. This force opposes the tendency of the ladder to slip away from the wall.
b) Calculate:
First, let's calculate the weight of the ladder:
W=mg=(10.0kg)(9.81m/s2)=98.1N
For the ladder to be in equilibrium, the net force and net torque must be zero.
Sum of forces in the horizontal (x) direction = 0:NA−Ff=0⟹NA=Ff(Equation1)
Sum of forces in the vertical (y) direction = 0:NB−W=0⟹NB=W=98.1N(Equation2)
Sum of moments about point B (bottom of the ladder) = 0:
Taking moments about B eliminates NB and Ff from the moment equation.
The weight W creates a clockwise moment. The perpendicular distance from B to the line of action of W is dCGcos(θ)=(2.0m)cos(60∘).
The normal force NA creates an anti-clockwise moment. The perpendicular distance from B to the line of action of NA is Lsin(θ)=(8.0m)sin(60∘).
W(dCGcos(60∘))=NA(Lsin(60∘))(98.1N)(2.0m×0.5)=NA(8.0m×23)98.1=NA(4.03)NA=4.0398.1=6.928298.1≈14.159N
i) The frictional force between the ladder and the ground (Ff).
From Equation 1, Ff=NA.
Ff=14.159N
Rounding to three significant figures:
Ff=14.2 N
ii) The resultant force at the bottom of the ladder.
The resultant force at the bottom (point B) is the vector sum of the normal force NB and the frictional force Ff. Since these forces are perpendicular, we use the Pythagorean theorem.
RB=NB2+Ff2RB=(98.1N)2+(14.159N)2RB=9623.61+200.477=9824.087≈99.116N
Rounding to three significant figures:
RB=99.1 N
iii) The coefficient of friction μ.
Assuming the ladder is in limiting equilibrium (or we are finding the minimum coefficient of static friction required to prevent slipping), the frictional force is given by Ff=μNB.
μ=NBFfμ=98.1N14.159N≈0.14433
Rounding to three significant figures:
μ=0.144
iv) The angle of friction θ.
The angle of friction θ is the angle whose tangent is the coefficient of friction.
tanθ=μθ=arctan(μ)=arctan(0.14433)θ≈8.209∘
Rounding to one decimal place:
θ=8.2∘
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Okay Nike🙃, let's solve question 2. Here's the information given for the non-uniform ladder: Length of ladder L = 8.0 m Mass of ladder m = 10.0 kg Center of gravity (CG) from the bottom B: d_CG = 2.0 m Angle with the vertical wall: = 30^.
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Okay Nike🙃, let's solve question 2. Here's the information given for the non-uniform ladder: Length of ladder L = 8.0 m Mass of ladder m = 10.0 kg Center of gravity (CG) from the bottom B: d_CG = 2.0 m Angle with the vertical wall: = 30^. This means the angle with the horizontal ground is = 90^ - 30^ = 60^. Upper end (A) against a smooth* wall (no friction). Lower end (B) on rough* ground (friction present). Acceleration due to gravity g = 9.81 m/s^2. a) Draw a free body diagram of the ladder. Imagine the ladder AB leaning against a vertical wall with its base on horizontal ground. Draw the ladder inclined at 60^ to the horizontal. Label the top end A and the bottom end B. Weight (W): A vertical arrow pointing downwards from the center of gravity G. G is located 2.0 m from B along the ladder. The magnitude is W = mg. Normal force at the wall (N_A): A horizontal arrow pointing away from the wall (to the right), acting at point A. Since the wall is smooth, there is no friction here. Normal force at the ground (N_B): A vertical arrow pointing upwards, acting at point B. Frictional force at the ground (F_f): A horizontal arrow pointing towards the wall (to the left), acting at point B. This force opposes the tendency of the ladder to slip away from the wall. b) Calculate: First, let's calculate the weight of the ladder: W = mg = (10.0 kg)(9.81 m/s^2) = 98.1 N For the ladder to be in equilibrium, the net force and net torque must be zero. Sum of forces in the horizontal (x) direction = 0: N_A - F_f = 0 N_A = F_f (Equation 1) Sum of forces in the vertical (y) direction = 0: N_B - W = 0 N_B = W = 98.1 N (Equation 2) Sum of moments about point B (bottom of the ladder) = 0: Taking moments about B eliminates N_B and F_f from the moment equation. The weight W creates a clockwise moment. The perpendicular distance from B to the line of action of W is d_CG () = (2.0 m) (60^). The normal force N_A creates an anti-clockwise moment. The perpendicular distance from B to the line of action of N_A is L () = (8.0 m) (60^). W (d_CG (60^)) = N_A (L (60^)) (98.1 N) (2.0 m × 0.5) = N_A (8.0 m × sqrt(3)2) 98.1 = N_A (4.0 sqrt(3)) N_A = (98.1)/(4.0 sqrt(3)) = (98.1)/(6.9282) ≈ 14.159 N i) The frictional force between the ladder and the ground (F_f). From Equation 1, F_f = N_A. F_f = 14.159 N Rounding to three significant figures: F_f = 14.2 N ii) The resultant force at the bottom of the ladder. The resultant force at the bottom (point B) is the vector sum of the normal force N_B and the frictional force F_f. Since these forces are perpendicular, we use the Pythagorean theorem. R_B = sqrt(N_B^2 + F_f^2) R_B = sqrt((98.1 N))^2 + (14.159 N)^2 R_B = sqrt(9623.61 + 200.477) = sqrt(9824.087) ≈ 99.116 N Rounding to three significant figures: R_B = 99.1 N iii) The coefficient of friction . Assuming the ladder is in limiting equilibrium (or we are finding the minimum coefficient of static friction required to prevent slipping), the frictional force is given by F_f = N_B. = (F_f)/(N_B) = 14.159 N98.1 N ≈ 0.14433 Rounding to three significant figures: = 0.144 iv) The angle of friction . The angle of friction is the angle whose tangent is the coefficient of friction. = = () = (0.14433) ≈ 8.209^ Rounding to one decimal place: = 8.2^ That's 2 down. 3 left today — send the next one.