Isaac (whose mass is 70 kg ) is taking a nap in the front of his 100−kg boat, which is floating at rest in a lake. After waking up, he's thirsty and heads toward the cooler in the back of his boat. (1) If he walks with a speed of 2 m/s (relative to the ground), what is the boat's velocity (relative to the ground) while he's walking? (2) What is the boats' velocity (relative to the ground) if he walks with a 2 m/s speed relative to the boat?