The volume of a sphere is given by the formula V = . Find the radius of a sphere whose volume is m3?
a.
15 m
b.
17 m
c.
1.7 m
d.
1.5 m
Solution:
V = 43πr3
3V / 4= πr3
3V4π = r3
r3 = 3V4π
r = 3V4π3 [Solve the formula for r.]
r = 3×14174×2273
r = 3×99×74×22×73
r = 2783
r =1.5
The radius of the sphere is 1.5 m.
Correct answer : (4)
2.
The kinetic energy, E, of a body moving with a velocity is given by the equation E = , where is the mass of the body. Find the mass of a body moving with a velocity 40 m/s and having an energy of 3000 N.
a.
4.05 kg
b.
3.75 kg
c.
3.65 kg
d.
6.75 kg
Solution:
E = 12mv2
2E = mv2
2Ev2 = m [Solve the equation for m.]
m = 2 × 300040 × 40 [Substitute: E = 3000, v = 40.]
m = 2×7540 = 3.75
The mass of the body is 3.75 kg.
Correct answer : (2)
3.
Solve the formula V = 2 for the variable . Indicate any restrictions on the values of the variables.
a.
= , V ≠ 0
b.
= , ≠ 0
c.
= , ≠ 0
d.
= , ≠ 0
Solution:
V = 1 / 3πr2h
3V = πr2h [Multiply both sides by 3.]
3Vπr2 = h [Divide both sides by πr2.]
h = 3Vπr2 [Symmetry property.]
The solution is h = 3Vπr2, r ≠ 0 [If r = 0, denominator becomes zero. Division by zero is undefined.]
Correct answer : (3)
4.
Solve the formula = 2( + ) for .
a.
= +
b.
=
c.
=
d.
= -
Solution:
p = 2(l + b)
p2 = l + b [Divide both sides by 2.]
p2 - l = b [Subtract l from both sides.]
b = p2 - l [Symmetry property.]
Correct answer : (4)
5.
Solve the formula = + for . Indicate any restrictions on the values of the variables.
a.
= , ≠ 0
b.
= , ≠ 0
c.
= ( + ), ≠ 0
d.
= + , ≠ 0
Solution:
v = u + at
v - u = at [Subtract u from both sides.]
v-ut = a [Divide both sides by t.]
a = v-ut [Symmetry property.]
The solution is a = v-ut, t ≠ 0 [The solution must exclude values of a variable that make the denominator zero.]
Correct answer : (2)
6.
Solve = + for .
a.
=
b.
= - -
c.
=
d.
=
Solution:
1f = 1u + 1v
1f - 1v = 1u [Subtract 1v from both sides.]
v-ffv = 1u [Simplify.]
fvv-f = u
Correct answer : (4)
7.
Solve = 2π( + ) for and indicate any restrictions on the values of the variables.