Chapter 10 Forces Objects will not begin to move or change motion until an unbalanced force acts on it. Newton’s 1st Law of Motion Inertia All mass resists a change in motion Depends on mass Greater mass = more inertia
Chapter 10 Forces Newton’s 2nd Law of Motion Changes in force & mass Acceleration increases when force (push or pull) increases when mass decreases
Chapter 10 Forces Determining Acceleration Acceleration (motion) depends on how much force is used and the amount of mass. acceleration = Force mass Newton’s 2nd Law of Motion
Chapter 10 Forces Newton’s 3 rd Law of Motion If one object exerts a force on another object, then the second object exerts a force back that is… equal in strength and opposite in direction on the first object.
Chapter 10 Forces Momentum “quantity of motion” depends on the mass and the velocity Momentum (p) = mass (kg) x velocity (m/s)
Chapter 10 Forces - Conservation of Momentum Momentum is conserved.. when 2 objects collide remains the same before and after the collision
Chapter 10 Forces Pg.392 Calculating Force A speedboat pulls a 55-kg water-skier. The skier to accelerates at 2.0 m/s 2. Calculate the net force that causes this acceleration. What is the question asking for? What information have you been given? Mass of the water-skier (m) = 55 kg Acceleration of the water-skier (a) = 2.0 m/s 2
Chapter 10 Forces Pg.392 Calculating Force Practice Problem What is the net force on a 1,000-kg object accelerating at 3 m/s 2 ? F = ma =1,000 kg x 3 m/s 2 = 3,000 N
Chapter 10 Forces Calculating Momentum Which has more momentum: a 3.0-kg sledgehammer swung at 1.5 m/s, or a 4.0-kg sledgehammer swung at 0.9 m/s? Read and Understand What information are you given? Mass of smaller sledgehammer = 3.0 kg Velocity of smaller sledgehammer = 1.5 m/s Mass of larger sledgehammer = 4.0 kg Velocity of larger sledgehammer = 0.9 m/s
Chapter 10 Forces Calculating Momentum Which has more momentum: a 3.0-kg sledgehammer swung at 1.5 m/s or a 4.0-kg sledgehammer swung at 0.9 m/s? What formula contains the given quantities and the unknown quantity? Momentum = Mass x Velocity p = mv Smaller sledgehammer = 3.0 km x 1.5 m/s = 4.5 kgm/s Larger sledgehammer = 4.0 km x 0.9 m/s = 3.6 kgm/s
Chapter 10 Forces Calculating Momentum Practice Problem A golf ball travels at 16 m/s, while a baseball moves at 7 m/s. The mass of the golf ball is kg and the mass of the baseball is 0.14 kg. Which has greater momentum? Golf ball: kg x 16 m/s = 0.72 kgm/s Baseball: 0.14 kg x 7 m/s = 0.98 kgm/s The baseball has greater momentum.
Chapter 10 Forces Calculating Momentum Practice Problem What is the momentum of a bird with a mass of kg flying at 15 m/s? 0.27 kgm/s (0.018 kg x 15 m/s = 0.27 kgm/s)
Chapter 10 Forces Section 5: Rockets and Satellites How does a rocket lift off the ground? What keeps a satellite in orbit?
Chapter 10 Forces What Is a Satellite? A projectile follows a curved path. The horizontal and vertical motions act independently.
Chapter 10 Forces What Is a Satellite? The faster a projectile is thrown, the father it travels before it hits the ground. A projectile with enough velocity moves in a circular orbit.
Chapter 10 Forces What Is a Satellite? Depending on their uses, artificial satellites orbit at different heights.
Chapter 10 Forces End of Section: Rockets and Satellites