Marta is standing 4 ft behind a fence 6 ft 6 in. tall. When she looks over the fence, she can just see the top edge of a buildin
g. She knows that the building is 32 ft 6 in. behind the fence. Her eyes are 5 ft from the ground. How tall is the building? Give your answer to the nearest half foot.
1 answer:
Answer: 93ft
Explanation: Martha's eyesight make an angle with the fence, this is solved as a triangle problem.
We first convert all the dimensions to inches using the fact that 12 inches make 1 ft.
To solve for the angle
Tan § = 18/48 = 0.375
§ = tan^-1 of 0.375 = 20.55°
This same angle elevates to the edge of the building
Tan 20.55 = 399/x
x = 399/tan 20.55
x = 1040 inches
Height of building = x + height of fence
Height of building = 1040 + 78 = 1118 inches
Converting back to ft it becomes
1118/12 = 93 ft 2 inches
Approximately 93ft
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Answer:
The amount of work done required to stretch spring by additional 4 cm is 64 J.
Explanation:
The energy used for stretching spring is given by the relation :
.......(1)
Here k is spring constant and x is the displacement of spring from its equilibrium position.
For stretch spring by 2.0 cm or 0.02 m, we need 8.0 J of energy. Hence, substitute the suitable values in equation (1).
k = 4 x 10⁴ N/m
Energy needed to stretch a spring by 6.0 cm can be determine by the equation (1).
Substitute 0.06 m for x and 4 x 10⁴ N/m for k in equation (1).
E = 72 J
But we already have 8.0 J. So, the extra energy needed to stretch spring by additional 4 cm is :
E = ( 72 - 8 ) J = 64 J
Answer:
Explanation:
mass, m = 12 kg
Force, F = 40 N
θ = 37° below the horizontal
(a)
Diagram is attached
(b) Let N be the normal reaction
According to the diagram
N + F Sin θ = m g
N = mg - F Sin θ
N = 12 x 9.8 - 40 x Sin 37
N = 117.6 - 24.07
N = 93.53
