8.0

1-2. A 63.0-kg sprinter starts a race with an acceleration of 4.20 m/s² . What is the net external force on him?If the sprinter accelerates at that rate for 20 m, and then maintains that velocity for the remainder of the 100-m dash, what will be his/her time for the race?

3. What net external force is exerted on a 1100-kg artillery shell fired from a battleship if the shell is accelerated at 2.4010⁴ m/s² ? What is the magnitude of the force exerted on the ship by the artillery shell? What is the acceleration of the battle ship if its mass is 6.8x10¹⁷ g?

4. What is the unit of force in the metric system? What base units does it break down into?

5. What is force due to gravity commonly called?

6. What is the direction of the weight vector, what sign would it have, and which direction would be considered opposite, which sign would the vector opposing the weight have?

7. When starting a foot race, a 70.0-kg sprinter exerts an average force of 650 N backward on the ground for 0.800 s. (a) What is his final speed? (b) How far does he travel?