Extended Response

80.

True or False—For vectors the order of addition is important.

True
False

81.

Consider five vectors a, b, c, d, and e. Is it true or false that their addition always results in a vector with a greater magnitude than if only two of the vectors were added?

True
False

82 .

For what angle of a vector is it possible that its magnitude will be equal to its y-component?

$θ = 0^{\circ}$
$θ = 45^{\circ}$
$θ = 60^{\circ}$
$θ = 90^{\circ}$

83.

True or False—If only the angles of two vectors are known, we can find the angle of their resultant addition vector.

True
False

84.

True or false—We can find the magnitude and direction of the resultant vector if we know the angles of two vectors and the magnitude of one.

True
False

85 .

Ignoring drag, what is the x-component of the acceleration of a projectile? Why?

The x-component of the acceleration of a projectile is $0$ because acceleration of a projectile is due to gravity, which acts in the y direction.
The x component of the acceleration of a projectile is $g$ because acceleration of a projectile is due to gravity, which acts in the x direction.
The x-component of the acceleration of a projectile is $0$ because acceleration of a projectile is due to gravity, which acts in the x direction.
The x-component of the acceleration of a projectile is $g$ because acceleration of a projectile is due to gravity, which acts in the y direction.

86 .

What is the optimum angle at which a projectile should be launched in order to cover the maximum distance?

$0^{\circ}$
$45^{\circ}$
$60^{\circ}$
$90^{\circ}$

87.

True or False—Friction varies from surface to surface because different substances have different degrees of roughness or smoothness.

True
False

88 .

As the angle of the incline gets larger, what happens to the magnitudes of the perpendicular and parallel components of gravitational force?

Both the perpendicular and the parallel component will decrease.
The perpendicular component will decrease and the parallel component will increase.
The perpendicular component will increase and the parallel component will decrease.
Both the perpendicular and the parallel component will increase.

89.

What physical characteristic of a system is its force constant related to?

The force constant k is related to the stiffness of a system: The larger the force constant, the stiffer the system.
The force constant k is related to the stiffness of a system: The larger the force constant, the looser the system.
The force constant k is related to the friction in the system: The larger the force constant, the greater the friction in the system.
The force constant k is related to the friction in the system: The larger the force constant, the lower the friction in the system.

90 .

How or why does a pendulum oscillate?

A pendulum oscillates due to applied force.
A pendulum oscillates due to the elastic nature of the string.
A pendulum oscillates due to restoring force arising from gravity.
A pendulum oscillates due to restoring force arising from tension in the string.

91 .

If a pendulum from earth is taken to the moon, will its frequency increase or decrease? Why?

It will increase because $g$ on the Moon is less than $g$ on Earth.
It will decrease because $g$ on the Moon is less than $g$ on Earth.
It will increase because $g$ on the Moon is greater than $g$ on Earth.
It will decrease because $g$ on the Moon is greater than $g$ on Earth.