2. Good Afternoon! 7/2/2016 Starter: If you want to accelerate a car at about 5 m/s how much force do you need? Today we will –Look at the gradesheet and hand back tests –Go through some net force problems and then –Work on some Force equations Answer: Newton’s 2 nd Law (F=ma) Starter: If you want to accelerate a car at about 5 m/s how much force do you need? Today we will –Look at the gradesheet and hand back tests –Go through some net force problems and then –Work on some Force equations Answer: Newton’s 2 nd Law (F=ma)

3. Some problems with Force

4. Net Force

5. You are on a dog sledding trip and the dogs are pulling the sled with a force of 278 N the friction is exerting a force of 56 N. Draw the forces and find F net.. 278 N 56 N F net = 222 N

6. Where does the ball Go? Please draw the forces that are acting on the volleyball Two volley ball players go up to spike the ball at the same time One applies a force of 12 Newtons and the other a force of 14 Newtons. 14 N12 N F net = 14 N -12 N = +2 N 2 N

7. Snoopy and Woodstock are out for a canoe trip. Snoopy is applying a force of 125 Newtons on the water. The fluid friction from the water is trying to slow them with a force of 3.5 Newtons. What is the Net force moving the canoe? 125 N3.5 N F net = +125 N + -3.5N = +121.5 N 121.5 N

8. Out on the soccer field you are running up to kick the ball at the same time that your opponent is trying to do the same thing. You end up kicking the ball at the same time with the same force but 90 0 apart.

9. How do Force, Mass and Acceleration Relate? If you use the same force to accelerate two masses the smaller one will have much more acceleration. If you want two masses to have the same acceleration you will need more force for the larger mass. If you use the same force to accelerate two masses the smaller one will have much more acceleration. If you want two masses to have the same acceleration you will need more force for the larger mass.

10. A few Equations (F=ma) You throw a 0.5 kg volley ball with a force of 8 N. What is it’s acceleration? (N stands for Newtons which is a measure of force and equal to 1 kg*m/s 2 ) You throw a 0.5 kg volley ball with a force of 8 N. What is it’s acceleration? (N stands for Newtons which is a measure of force and equal to 1 kg*m/s 2 ) N = kg  m s 2

11. Volleyball F = 8 N m = 0.5 kg a = ? F = 8 N m = 0.5 kg a = ? F  ma m  m F m  a

12. A rider on a motorcycle goes from 0 m/s to 13 m/s in 2.5 seconds. The rider and the motorcycle have a mass of 324 Kg. What force would be exerted on any object the bike and rider ran into?

13. Motorcycle F = ? m = 324 kg a = F = ? m = 324 kg a =

14. You push a car with a force of 2100 Newtons. The car changes velocity at a rate of 1.4 m/s every second. What is the car’s mass?

15. Car F = 2100 N m = ? a = 1.4 m/s 2 F = 2100 N m = ? a = 1.4 m/s 2