NEWTONS LAWS OF MOTION Philosophiae Naturalis Principia Mathematica

NEWTON'S LAWS OF MOTION Philosophiae Naturalis Principia Mathematica (1686)

NEWTON'S LAWS OF MOTION Newton’s 1 st Law of Motion Law of Inertia A body at rest, or in constant motion will remain at rest, or in constant motion unless acted upon by a NET FORCE. Inertia is the resistance of an object to motion – The amount of resistance varies directly with the mass.

NEWTON'S LAWS OF MOTION

NEWTON'S LAWS OF MOTION Newton’s 1 st Law of Motion

NEWTON'S LAWS OF MOTION Newton’s 2 nd Law of Motion 1. The acceleration is in the direction of the net force. 2. The acceleration is directly proportional to the net force, and inversely proportional to the mass.

NEWTON'S LAWS OF MOTION Newton’s 2 nd Law of Motion Force causes acceleration F F F More force = more acceleration Ø Doubling the force doubles the acceleration Ø M M M a a a

NEWTON'S LAWS OF MOTION Acceleration: Time Rate of change of velocity (Requires a Net Force) A NET FORCE always is needed to produce an acceleration

NEWTON'S LAWS OF MOTION Newton’s 2 nd Law of Motion m - measured in kg a - measured in m/s 2 Therefore: Force – measured in kg x m/s 2 - Newton (N)

NEWTON'S LAWS OF MOTION Acceleration due to Gravity Force (gravity) is same for all objects regardless of mass. 1. Gravity acceleration force on earth is: g = 9. 8 m/s 2. 2. The ratio of the gravitational force to the mass is the same for all objects.

NEWTON'S LAWS OF MOTION Newton’s 2 nd Law of Motion How much horizontal net force is required to accelerate a 1, 000 kg car at 2 m/s 2?

NEWTON'S LAWS OF MOTION What does the slope of a Force vs. Acceleration graph give? Slope = Mass Force (N) Acceleration (m/s 2)

NEWTON'S LAWS OF MOTION Newton’s 3 rd Law of Motion “Law of Action and Reaction” When one body exerts a force on another body, the second exerts an equal but opposite force back on the 1 st body “For every action (force) there is an equal and opposite reaction (force)” Can you identify 6 pairs of action reaction forces?

NEWTON'S LAWS OF MOTION Newton’s 3 rd Law of Motion

NEWTON'S LAWS OF MOTION Newton’s 3 rd Law of Motion For every action (force) there is an equal and opposite reaction (force. )

NEWTON'S LAWS OF MOTION Newton’s 3 rd Law of Motion Demolition Derby When two cars of different size collide, the forces on each is the SAME in magnitude (but in opposite direction). However, the same force on a smaller car means a bigger acceleration!

NEWTON'S LAWS OF MOTION Newton’s 3 rd Law of Motion

NEWTON'S LAWS OF MOTION

NEWTON'S LAWS OF MOTION A mass of 20 kg is pulled horizontally by a force of 25 N at an angle of 300 to the horizontal, if the frictional force is 3 Newtons: 1. Draw a free body diagram showing all the forces on the block. 2. Find the normal force 3. Calculate the acceleration of the block

NEWTON'S LAWS OF MOTION Find the tension in each cord for the systems shown in Figure. (Neglect the mass of the cords!).

NEWTON'S LAWS OF MOTION A 25 -kg block is initially at rest on a horizontal surface. A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed. Find the coefficients of static and kinetic friction from this information

NEWTON'S LAWS OF MOTION What is the magnitude of the acceleration of a 2 kg object when the net force on the object is 10 N? 1. 10 m/s 2 2. 20 m/s 2 3. 5 m/s 2 10 Newtons

NEWTON'S LAWS OF MOTION A 0. 5 kg model airplane is initially at rest. If a 10 N force is applied to it for 2 s, its final velocity would be 1. 2. 3. 4. 5. 5 m/s 20 m/s 40 m/s 10 m/s 30 m/s 10 N

NEWTON'S LAWS OF MOTION A 15 N force is applied to a mass M that is adjacent to the wall, as shown below. If the mass is 2 kg, the force that the wall exerts on the mass is equal to: 1. 2. 3. 4. 5. 0 N 2 N 15 N 19. 6 N 30 N

NEWTON'S LAWS OF MOTION In the diagram below, a force F is applied to a mass M at an angle with the horizontal. What is the magnitude of the normal force? 1. 2. 3. 4. 5. Mg – F sin Mg + F sin Mg / F sin / Mg Mg

NEWTON'S LAWS OF MOTION In the figure, the coefficient of sliding friction between the small block and the table top is 0. 2. If the pulley is frictionless and massless what will be the acceleration of the blocks once they are released from rest? 1. 2. 3. 4. 5. 0. 5 g 0. 6 g 0. 7 g 0. 8 g 0. 9 g

NEWTON'S LAWS OF MOTION A mass M rests on top of a frictionless inclined plane. Which of the following statements is correct about the normal force acting on the mass as the angle of Elevation increases? 1. 2. 3. 4. 5. The normal force increases The normal force decreases The normal force increases, then decreases The normal force decreases, then increases The normal force remains constant

NEWTON'S LAWS OF MOTION The coefficient of static friction between a box and a ramp is 0. 5. The ramp’s incline angle is 30 degrees. If the box Is placed at rest on the ramp, the box will: 1. 2. 3. 4. 5. Accelerate down the ramp Accelerate briefly down the ramp then slow down and stop Move with constant velocity down the ramp Remain at rest None of the above

NEWTON'S LAWS OF MOTION When bottom (Smoothest) block is struck with hammer, it slides quickly from under the top blocks, which drop very nearly straight down.

NEWTON'S LAWS OF MOTION

NEWTON'S LAWS OF MOTION