Câu 24. Một viên bi có khối lượng 300 g chuyển động với tốc độ 0,8 ms tới va chạm vào một viên bi thứ hai có khối lượng 200 g đang đứng yên. Sau va chạm hai viên bị dính vào nhau và chuyển động với cùng
một vận tốc. Nhiệt lượng tỏa ra trong va chạm này bằng
A. 4,38 m).
B. 4,83 m).
C. 38,4 mj.
D. 34,8 m).
Con 25 un bon

Which of the following represents an upright image? a. -do b. +m c. -m d. +do

James is trying to prove newton's 2nd law of motion. he tries to move four different objects with different masses, shapes, and sizes from point a to point b. the objects are a toy car, a car, a refrigerator, and a kitchen table. after some experimentation, he finds that force is dependent on the mass of the object, rather than it's size or shape. the object that takes the most force to move is the

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 ⇒