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Warm up Vocabulary: Force= mass x acceleration Circle one. 1. An object with More/less mass will have a greater gravitational pull on other objects. 2. An object that is closer to/ further from a second object will have a greater gravitational pull. 3. Generally will More/Less force be needed to pull or push an object? 4. Will pushing an object with More/ Less force cause it to have a greater acceleration (change in speed)? Objective •SWBAT answer questions IOT explain Newton’s first and second laws of motion 1st Law of Newton • Newton’s 1st law of motion= an object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted on by an unbalanced force. • i. Example: A tennis racket stopping a ball. Gravity and friction are unbalanced forces that changes an object’s motion. • ii. Example: Real life: when the alarm clock rings, do you immediately jump up and get ready for school? Usually, no. You were initially at rest and you want to stay at rest. This is an example of inertia. • Iii. Inertia= the tendency of an object to resist a change in motion. The greater the mass of an object, the greater its inertia, and the greater the force required to change its motion. 2nd Law of Motion • A. Newton’s 2nd law of motion= acceleration depends on the object’s mass and on the net force acting on the object. • B. Acceleration= Net force/mass a=Fnet/m. • Acceleration is measured in m/s2 and mass is measured in kg. • C. In other words: Newton’s 2nd law of motion = the net force acting on an object depends on the object’s mass and acceleration. • i. Force= mass x acceleration F=ma. Mass is measured in kg and acceleration is measured in m/s2. The units for force can be in Newtons(N) or kg*m/s2. Sample Problem • A speedboat pulls a 55-kg water skier. The force causes the skier to accelerate at 2.0 m/s2. calculate the net force that causes this acceleration. • i. Step 1: Identify the needed information! In the equation F=ma, you need mass and acceleration. Can you find them in the problem? Steps to solving • Mass (m)= 55 kg • Acceleration (a)= 2.0m/s2 • ii. Step 2: “Plug in” the numbers to the equation F= (55kg)(2.0m/s2) • Iii. Step 3: Solve the problem and check your work! F=110kg*m/s2 or 110 N Demonstrations • Watch the different demos in order to understand Newton’s laws. • Chair • Bucket Evaluation • Complete guided worksheet #1-10 in your classwork section of your binder. Exit Slip • 1. Objects at rest will stay ____________. • 2. How would you describe the law of inertia? • 3. According to Newton’s second law, if you increase the mass of an object, you will also need to Increase/decrease (circle one) the force you use to move it. • Force= ______________x ______________