1 / 11

Newton’s 2 nd & 3 rd Laws

Newton’s 2 nd & 3 rd Laws. A couple things to keep straight. Mass = the amount of “stuff” something is made of. Weight = the measure of the force of gravity on an object. A couple of things to remember. You can use Newton’s 2 nd Law to solve for weight.

miya
Download Presentation

Newton’s 2 nd & 3 rd Laws

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Newton’s 2nd & 3rd Laws

  2. A couple things to keep straight • Mass = the amount of “stuff” something is made of. • Weight = the measure of the force of gravity on an object.

  3. A couple of things to remember • You can use Newton’s 2nd Law to solve for weight. • Weight = force of gravity acting on a specific object. (acceleration due to gravity is -9.8m/s2 ) therefore…

  4. How to solve for weight • Fnet = m x a (2nd Law) • Weight = mass of object x acc. due to gravity • F(grav) = m x acc (due to “g”) • Weight = m x acc (due to “g”) so: F(grav) = weight (Good formula to remember = F(grav) = m x g)

  5. Standard Units of Force • Force measured in Newtons (N) • 1 N = 1 kg x m/s2 • 1 Kg weighs approximately 2.2 lbs • 1 kg weighs approximately 10 N • So…10 N = 2.2 lbs

  6. Solving a Force Problem with Newton’s 2nd Law • Fnet= sum of all forces • If there is no motion in one direction (“X” or “Y”), forces are balanced…nothing to solve. • Must determine direction of motion and solve for those net forces • Fnet= Fapp - Ff OR Fnet = Fn – Fg

  7. A question to make you think??? • Is the force of gravity the same for all objects on Earth? Answer… NO!!! Due to mass, however acceleration is the same!

  8. A couple things about Newton’s 3rd Law • Forces always occur in pairs • “For every action there is an equal & opposite reaction” Fa on b = -Fb on a Ex. Car driving down the road. What are the forces?

  9. A couple things about Newton’s 3rd Law (cont.) What forces are acting on the car? Force of grav. (down) / Normal Force (up) Force of friction (road on car) / Force of friction (car on road)

  10. A couple things about Newton’s 3rd Law (cont.) • Drop a softball (mass 0.18Kg) ? What is the force on Earth due to the ball ? What is the Earth’s acceleration (mass of Earth = 6.0 x 1024 Kg) hint: use Fg = mg

  11. Softball Answer • F(grav) = (0.18 kg) x (-9.8 m/s2) F = -1.8 N (therefore, force on ball from Earth = 1.8 • Acceleration = 1.8 N = (6.0E24)a 3.1E-25 m/s2

More Related