Typically your target heart rate is used for that. you can track and guide your exercise intensity by calculating your target heart rate range
Protons have positive charges
C is the right answer
I hooe this helps
Explanation:
It is given that,
Mass of the Cadillac, 
Speed of Cadillac,
(towards north)
Mass of Volkswagen,
The cars stuck together and slid to a halt, leaving skid marks angled 35 degrees north of east.
According to the law of conservation of momentum,
The momentum along x axis,
............(1)
The momentum along y axis,
...........(2)
From equation (1) and (2) it is clear that,




So, the Volkswagen going just before the impact is 8.72 m/s. Hence, this is the required solution.