(A) Calculate the acceleration of gravity, gC, on Ceres
Apply the kinematics displacement equation to the falling rock.
(1)
Δx = 1/2at2 + v0t
Substitute Δx = -10.0 m, v0 = 0, a = -gC, and t = 8.06 s, and solve for the gravitational acceleration on Ceres, gC.
-10.0 m = -1/2gC(8.06 s)2 → gC = 0.308 m/s2
(B) Find the mass of Ceres.
Equate the weight of the rock on Ceres to the gravitational force acting on the rock.
mgC = G | MCm |
RC2 |
Solve for the mass of Ceres, MC.
MC = | gCRC2 | = 1.20 1021 kg |
G |
(C) Calculate the acceleration of gravity at a height of 50.0 km above the surface of Ceres.
Equate the weight at 50.0 km to the gravitational force.
mg'C = G | mMC |
r2 |
Cancel m, then substitute r = 5.60 105 m and the mass of Ceres.
g'C = G | MC |
r2 |
= (6.67 10-11 kg-1m3s-2) | 1.20 1021 kg |
(5.60 105 m)2 |
= 0.255 m/s2
PRACTICE IT
Use the worked example above to help you solve this problem. An astronaut standing on the surface of Ceres, the largest asteroid, drops a rock from a height of 10.0 m. It takes 8.06 s to hit the ground.
(a) Calculate the acceleration of gravity on
Ceres.
m/s2
(b) Find the mass of Ceres, given that the radius
of Ceres is RC = 5.10 102
km.
kg
(c) Calculate the gravitational acceleration 53.0
km from the surface of Ceres.
m/s2
EXERCISE
An object takes 2.95 s to fall 4.95 m on a certain planet.
(a) Find the acceleration due to gravity on the planet.
m/s2
(b) Find the planet's mass if its radius is 5250 km.
kg
Get Answers For Free
Most questions answered within 1 hours.