QUESTION 1 A 20 kg block, resting on rough horizontal surface, is connected to blocks P and Q by a light
inextensible string, moving over a frictionless pulley. Blocks P and Q are glued together and
have a combined mass of m. A force of 35 N is now applied to the 20 kg block at an angle of 40°
with the horizontal as shown below.
35 N
20 kg
P
The 20 kg block experiences a frictional force of magnitude of 5 N as it moves to the RIGHT at a
CONSTANT SPEED.
(2)
Calculate the combined mass m of the two blocks

Janelle made a hypothesis bout the uneven temperatures inside her house during winter. she believes that 50% of the ducts are blocked and she plans to investigate. if she wants to prove her hypothesis using scientific processes what should she do next?

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 ⇒

The electronic structure or chlorine is 2.8.7 what is the electronic structure of fluorine?