In: Physics
1.Three identical very dense masses of 3500 kg each are placed on the x axis. One mass is at x1 = -120 cm , one is at the origin, and one is at x2 = 300 cm .
What is the magnitude of the net gravitational force Fgrav on the mass at the origin due to the other two masses?
Take the gravitational constant to be G = 6.67×10−11 N⋅m2/kg2 .
Express your answer in newtons to three significant figures.
2.Three identical very dense masses of 5000 kg each are placed on the x axis. One mass is at x1 = -100 cm , one is at the origin, and one is at x2 = 310 cm .
What is the magnitude of the net gravitational force Fgrav on the mass at the origin due to the other two masses?
Take the gravitational constant to be G = 6.67×10−11 N⋅m2/kg2 .
Express your answer in newtons to three significant figures.
1.
Gravitational force is given by:
F = G*m1*m2/R^2
Net force on the mass at origin will be
Fnet = F2 - F1
m1 = m2 = m3 = m
Since gravitational force is always attractive force, So force due to mass at x1 will be towards -ve x-axis and force due to mass at x2 will be towards +ve x-axis.
Fnet = G*m*m/x1^2 - G*m*m/x2^2
Fnet = G*m^2*(1/x1^2 - 1/x2^2)
x1 = -120 cm = 1.20 m
x2 = 300 cm = 3.00 m
Using given values:
Fnet = 6.67*10^-11*3500^2*(1/3.00^2 - 1/1.20^2)
Fnet = -4.77*10^-4 N
Magnitude of F = |F| = 4.77*10^-4 N
(-ve sign means Net force will be towards -ve x-axis)
2.
Gravitational force is given by:
F = G*m1*m2/R^2
Net force on the mass at origin will be
Fnet = F2 - F1
m1 = m2 = m3 = m
Since gravitational force is always attractive force, So force due to mass at x1 will be towards -ve x-axis and force due to mass at x2 will be towards +ve x-axis.
Fnet = G*m*m/x1^2 - G*m*m/x2^2
Fnet = G*m^2*(1/x1^2 - 1/x2^2)
x1 = -100 cm = 1.00 m
x2 = 310 cm = 3.10 m
Using given values:
Fnet = 6.67*10^-11*5000^2*(1/3.10^2 - 1/1.00^2)
Fnet = -14.9*10^-4 N
Magnitude of F = |F| = 14.9*10^-4 N
(-ve sign means Net force will be towards -ve x-axis)
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