Below are 4 statements about acceleration. Which statement is NOT correct?
A. acceleration always involves changing speed.
B. changing direction always involves acceleration.
C. changing speed always involves acceleration.
D. circular motion always involves acceleration.

Bob camina 200 m sur, luego trota 400 m suroeste, luego camina 200 m en una dirección 30? norte del este. a. dibuje una gráfica de los movimientos de bob. use una regla y transportador. b. use método gráfico y analíitico para hallar el desplazamiento total que bob recorrió. (magnitud y dirección) c. compare los resultados obtenidos por el método gráfico y analítico. (por ciento de diferencia).

Alarge box of mass m is pulled across a horizontal frictionless surface by a horizontal rope with tension t. a small box of mass m sits on top of the large box. the coefficients of static and

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.