Radioactive isotopes are useful for
A) dating the ages of objects.
B) tracing the path of certain chemicals.
C) cancer therapy.
D) All of the above.
E) None of the above.
Question 2
A 2.0-kg ball is moving with a constant speed of 5.0 m/s in a horizontal circle whose diameter is 1.0 m. What is the magnitude of the sum of the forces exerted on the ball?
A) 0 N
B) 20 N
C) 40 N
D) 50 N
E) 100 N