4. a cow has eaten 1500 kj of stored chemical energy in the form of food. 945 kj
is excreted as waste products. 495 kj is 'used for respiration.
a. how much of the original 1500 kj is stored as chemical energy in the
tissues of the cow? (1)
w b. the answer to part a is all the energy that can be transferred to a human.
calculate the efficiency of the energy transfer to the human. (hint: how
much of the original 1500 kj is transferred to the (3)

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.