Transcript Review - Fort Thomas Independent Schools

Review
Motion and Forces Test
Starter Q 12-5 Forces
• Two different forces interact on a cart, one is 8
N and the other is 6 N. What is the minimum
and maximum net force that could be acting
on the cart? Draw two free body diagrams
respresenting
Forces
• Two different forces interact on a cart, one is 8
N and the other is 6 N. What is the minimum
and maximum net force that could be acting
on the cart?
• Answer: minimum net force 8 N- 6 N = 2 N
maximum net force 8 N + 6 N = 14 N
Forces
• A 4000 N car is driving down the road at a
constant velocity of 60 mph north. The force
that the engine applies to the wheels is 2500
N. Find the normal force acting on the car and
the combined amount of air resistance and
friction acting on the car. Draw a free body
diagram showing all four forces.
Forces
• A 4000 N car is driving down the road at a
constant velocity of 60 mph north. The force that
the engine applies to the wheels is 2500 N. Find
the normal force acting on the car and the
combined amount of air resistance and friction
acting on the car. Draw a free body diagram
showing all four forces.
• Answer:
– F normal = 4000 N
– F air and friction = 2500 N
Forces
• The same 4000 N car is driving down the road
and accelerates to the north using a force of
3200 N. Find the net force acting on the car
and the direction that the net force is acting.
Assume the same air resistance and friction as
in the previous problem. Draw a free body
diagram showing all four forces.
Forces
• The same 4000 N car is driving down the road
and accelerates to the north using a force of
3200 N. Find the net force acting on the car
and the direction that the net force is acting.
Assume the same air resistance and friction as
in the previous problem. Draw a free body
diagram showing all four forces.
• Answer:
– F net = 3200 N – 2500 N = 700 N to the north
Determine the net force acting on the box in each
panel.
A
50 N
B
50 N
50 N
C
30 N
50 N
70 N
A
B
Which panel(s) show unbalanced force? ________________
Which panel(s) show balanced force? ________________
Which panel(s) show acceleration? ________________
Which panel(s) show net force > zero? ________________
C
Identify the two forces acting in this photograph. Then complete
the fill-in-the-blank question to the left.
(zero, unbalanced, increasing,
balanced, 9.8 m/s2, and constant.)
This man is falling at terminal velocity.
At terminal velocity, the forces are
_____________, the falling speed is
_____________ and the rate of
acceleration is ____________.
Identify the two forces acting in this photograph. Then complete
the fill-in-the-blank question to the left.
(zero, unbalanced,
increasing, balanced, 9.8
m/s2, and constant.)
This man is falling at
terminal velocity. At
terminal velocity, the forces
are __balanced_, the
falling speed is
____constant__ and the
rate of acceleration is zero.
Air resistance
Force of gravity or
weight
Least surface
area?
Falling Objects
Greatest
weight?
Greatest surface
area?
Which object hits the ground first? Last? Which experiences the
greatest net force (difference between air resistance and weight or F
grav)? Which will experience the greatest rate of acceleration? The
least?
Least surface
area?
Falling Objects
Greatest
weight?
Greatest
Acceleration?
Least
Acceleration?
Greatest
Net
Force?
Greatest surface
area?
Which object hits the ground first? Last? Which experiences the
greatest net force (difference between air resistance and weight or F
grav)? Which will experience the greatest rate of acceleration? The
least?
Which two factors influence the force
of air resistance acting on a falling
object?
Surface area
and
Speed
Which two factors influence the
amount of gravity that exists between
two objects?
Mass of the objects and the distance
between the objects.
Which two motions act at the same
time to cause an object to act as a
projectile?
Horizontal motion (constant speed)
vertical motion (acceleration)