008 10.0 points A uniform horizontal rod of mass 1.5 kg and
length 2.1 m is free to pivot about one end
as shown. The moment of inertia of the rod
about an axis perpendicular to the rod and
through the center of mass is given by I
ml2
12
F
570
-pivot
1.5 kg
2.1 m
If a 7.7 N force at an angle of 57° to the hor-
izontal acts on the rod as shown, what is the
magnitude of the resulting angular accelera-
tion about the pivot point? The acceleration
of gravity is 9.8 m/s.
Answer in units of rad/s2.

Aregion of space in which a measurable gravitational force is indicated by the force exerted on a test mass is called

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒

Positrons are spontaneously emitted from the nuclei of