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Slide1: 50 Newton is about equal to. 10 lbs 23 lbs 50 lbs 110 lbs 250 lbs. Slide 2 What is a net force?. A force acting on an object All the forces acting downward The combination of all the forces When all the forces cancel out.
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Slide1: 50 Newton is about equal to 10lbs 23lbs 50 lbs 110 lbs 250lbs
Slide 2What is a net force? • A force acting on an object • All the forces acting downward • The combination of all the forces • When all the forces cancel out
Slide 3You throw a rock in space. What is required to keep the rock moving at a constant velocity? A constant force while its moving A very small force once its moving nothing
Slide 4A book is resting on a table. Since the book is not moving • There is not a force acting on it • The table is pushing up with a greater force than gravity is pulling down with • Gravity is pulling down with a greater force than the table is pushing up with • The net force on the book must be zero
Slide 5A constant (and not zero) net force is applied to a person on rollerblades. The person will… Move at a constant velocity Continually change velocity Move for a while at a constant velocity and then change velocity It depends on how big the frictional forces are
Slide 6There is a zero net force acting on a person on rollerblades. You could say • The person is not moving • The person is moving at a constant velocity (not zero) • The person is accelerating • Not enough information to tell
Slide 7A person on rollerblades is pushed with a constant force of 10 N and experiences an unknown force of friction. If the person moves at a constant velocity of 2 m/s, you could say… • friction = 0 N • friction = 5 N • friction= 10 N • friction = 20 N
Slide 8To change the velocity of an object, you need • forces • unbalanced forces • inertia • nothing