Download Chapter 12 Study guide

Chapter 12 Study guide
Name____________________per____
1) What is the SI unit of force? Also, write it as the combination of kg, m, and s. (12.1)
2) What happens when an unbalanced force acts on an object? (12.1)
3) When a pair of balanced forces acts on an object, (12.1)
What is the net force that results?
What will happen to an object that is not moving?
What will happen to an object that is moving?
4) What kind of friction occurs: (12.1)
As a spoon stirs cake batter?
As the ball bearings in a skateboard wheel turn?
As a pop can slides across a table?
As you walk?
5) As you push a cereal box across a table, how does the sliding friction act on the cereal box? (12.1)
6) What are the forces acting on a falling feather? (12.1)
7) How does an open parachute increases air resistance of a falling sky-diver? (12.1)
Figure 12-1
8) Figure 12-1 shows the motion of three balls. (12.1)
The curved paths followed by balls B and C are examples of what type of motion?
Each ball started moving at the same time. Ball A was dropped and balls B and C were thrown sideways. Compare the times for each ball to reach the ground. Explain.
9) Projectile motion is caused by what force(s)? (2 different forces, each with a direction) (12.1)
10) What is the property of matter that resists changes in motion called? (12.2)
11) Why do you fly through the windshield of a car in a head-on crash if you are not wearing your seatbelt? (12.2)
12) How is your weight related to your mass? (12.2)
13) The acceleration due to gravity on the surface of the moon is about one-sixth the acceleration due to
gravity on Earth’s surface. (12.2)
What is the weight of an astronaut on the surface of the moon compared to his weight on Earth?
What is the mass of an astronaut on the surface of the moon compared to his mass on Earth?
14) What do each of Newton’s laws of motion describe? (12.2 & 12.3)
First
Second
Third
15) What is conserved when two objects collide in a closed system? (12.3)
16) What force is responsible for the repulsion between two positively-charged particles? (12.4)
17) What happens when opposite poles of two magnets are brought together? (12.4)
18) Which universal force acts only on the protons and neutrons in a nucleus? (12.4)
19) Which of the universal forces is the most effective over long distances? (12.4)
20) As a space probe travels far away from Earth: (12.4)
What happens to its weight?
What happens to its mass?
21) What happens to gravitational forces when? (12.4)
Mass increases
Mass decreases
Distance increases
Distance decreases
22) What is the force that keeps an object moving in a circle? It is a result of what two forces? (12.4)
23) How does momentum change when (12.3)
The mass of the object increases?
The mass of the object decreases?
The velocity of the object increases?
The velocity of the object decreases?
24) Define momentum. (12.3)
25) Describe conservation of momentum. (12.3)
26) Define force. (12.1)
27) Define net force. (12.1)
28) Describe what happens to the motion of an object if (12.1)
The net force is zero
The net force in 3N left
The forces balance
The forces are not balanced
29) Regarding friction: (12.1)
Define it.
In what direction does it always act?
30) List the four types of friction in order of strength (as well as possible), greatest to least, describe
each, give an example of each. (12.1)
31) When you push on a wall, what does the wall do? (12.3)
32) Define inertia. (12.3)
33) How are the size and direction of action-reaction forces related? (12.3)
34) Why don’t action-reaction forces cancel each other? (12.3)
35) How do gravity and air resistance affect a falling object? (12.1)
36) What is terminal velocity? (12.1)
37) What is the primary cause of Earth’s ocean tides? - be specific!!! (12.3)
Problem Examples
For every problem, you will have to give:
A list of all needed information
The formula you will use
The setup (the values plugged into the formula)
The answer
The correct units
1) A boy pushes forward a cart of groceries with a total mass of 85.0 kg. What js the acceleration of
the cart if the net force on the cart is 120.0N. (12.2)
2) What is the upward acceleration of a helicopter with a mass of 6500 kg if a net force of 13,500N acts
on it in an upward direction? (12.2)
3) A toy car with a mass of 120 g accelerates at a rate of 1.5 m/s2 in the forward direction. What is the
net force acting on the car? (12.2)
4) If the gravitational force acting on a ball is 2.6 N, what is the baseball’s mass in kg? (12.2)
5) A 5600 g dog runs 600 meters in 16 seconds. (12.3)
a) What is its velocity? (m/s)
b) What is its momentum (kg • m/s)
6) A 85 kg man rides his bicycle 5 km in 4 minutes. (12.3)
a) What is his velocity? (m/s)
b) What is his momentum (kg • m/s)
7) The dog eats the man’s leg, then continues running at the same speed, would the dog’s momentum:
increase, decrease, or stay the same? Explain. (12.3)
8) A 2000 lb sailboat travels 4.3 km in 15minutes. (12.3)
a) What is its velocity? (m/s)
b) What is its momentum (kg • m/s)
c) What would the momentum be if the boat was 4000 lb?
9) A 25 kg child runs 1.5 km in 12 minutes. (12.3)
a) What is her velocity (m/s)
b) What is her momentum (kg • m/s)
10) Adam threw a ball with a momentum of 5 kg • m/s
(12.3)
Bill threw a ball with a momentum of 2.6 kg • m/s
Casey threw a ball with a momentum of 4.3 kg • m/s
Who threw the ball the fastest? ____________________________________
Explain____________________________________________________________________
Four identical balls are rolled off a table. Their paths are shown below. (12.1)
A
B
C
D
11.) Which ball(s) had the greatest horizontal force?_____________________
Explain:___________________________________________________________________
_____________________________________________________________________________
12.) If all 4 balls were launched at exactly the same time, which ball(s) would hit the floor 1st?
Explain: ______________________________________________________________________
________________________________________________________________________________
The four balls below are dropped from exactly the same height (30m), at exactly the same time in a
room full of air.
(12.1)
A
B
C
D
5g
45g
25g
60g
13.) a.)Which ball(s) would hit the floor first?___________________
Explain: __________________________________________________________________________
__________________________________________________________________________________
b.) Which ball(s) would hit the floor first if all of the air had been pumped out of the
room?___________________
Explain:_____________________________________________________________________________
____________________________________________________________________________________
Bingo has live on Earth (mass = x) all his life. But now he’s restless and decides to explore his solar
system. Pictured below are 5 planets (A,B,C,D,E) in Bingo’s solar system. Their masses are listed below the planet (given as a number multiplied by the mass of Earth).
(12.2)
Earth
m=x
A
m = .5x
Bingo’s mass on Earth = 85 kg
B
C
m = 1.75x
m = .2x
D
E
m = 1.3x
m=x
Bingo’s weight on Earth = 187 lbs
14.) On which planet would Bingo weigh the most?____________
Explain:_________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
15.) How much would Bingo weigh on planet E?________________________
16.) On which planet(s) would he weigh less than on Earth?
Explain: _________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
17.) On which planet(s) would his mass increase?_________________________
Explain: _________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________