Transcript Newton’s Laws Problems - Lompoc Unified School District

Newton’s Laws Problems
Example
 Three kids are fighting over the same toy. One pulls the toy
with a force of 20N (E), another pulls with a force of 15N
(15°N of W), and the third pull with 22N (5°W of S).
a) Find the total force on the toy.
b) What is the toy’s acceleration?
Example
 A child pulls on a wooden toy attached to a string. The toy
has a mass of 5kg and the child pull on the string with a force
of 25N at an angle of 50° with the horizontal. Assuming no
friction.
a) Draw the free body diagram.
b) Calculate the normal force.
c) Determine the acceleration of the toy.
Example
 Working in his yard, a man pushes on a 50kg lawnmower. He
exerts a force of 200N on the handle that makes and angle of
60° with the horizontal.
a) Draw the free body diagram.
b) Determine the Normal force.
c) Find the acceleration of the mower.
Example
 A 65kg man is standing on a bathroom scale in an elevator.
What will the scale read when,
a) the elevator is at rest
b) the elevator accelerates up at 3.0 m/s2
c) the elevator accelerates down at 3.0 m/s2
Example
 A .75kg mass is at rest on a frictionless, horizontal table. It is
connected by a light string running over a pulley to a hanging
.50kg mass.
a) Draw the free body diagram
b) Calculate the acceleration of the mass.
Objects on Inclines
Example
A 5.0 kg block is placed on a 30o frictionless inclined plane.
Draw the free body diagram and calculate the acceleration of
the block down the incline.
Example
If the block in the previous problem experiences friction and
slides down the plane at a constant velocity of 10 m/s, draw
the free body diagram and calculate the force of friction
Example
 A 3.0kg mass is resting on a frictionless incline of 30°. It is
connected by a light string running over a pulley to a hanging
mass of 2.0kg.
a) What is the tension on the string?
b) What is the acceleration of the mass?