Which of the following is a closed system or very close to a closed system? a. a block of iron sealed in a vacuum chamber b. a dish of ice cream sitting in the sunlight c. a stick of dynamite during an explosion d. a stalled car in a snowstorm

Your target variable is δf, the magnitude of the difference in frequency between the waves emitted from the sonar device and the waves received by the device after reflecting off the whale. write an expression for δf in terms of the relevant frequencies using the subscript notation introduced above.

22. the effect of threshold braking is to a cause skids. b. lock wheels. c. prevent locking of wheels. d. increase stopping distance.

Select all that applywhat are some basic resources a family is expected to provide for children? educationclothesspending