Ten Kinematic Problems Grade 12 Physics

In summary, the homework statement asks for the equations of motion for an object dropped from a high place. An object such as a ball will have a velocity and acceleration vector in the same direction. An object such as a cannonball launched vertically upward will have a velocity vector upward and an acceleration vector down due to gravity which means the velocity and acceleration vectors are in opposite directions momentarily. Both bullets hit the ground at the same time because both objects have the same initial velocity of zero and acceleration of gravity in the y-component. The x-component does not affect the y-component which is why it is ignored. The magnitude of the football's displacement is 38m.
  • #1
Steb
5
0

Homework Statement


See attachment, it is the question sheet.


Homework Equations



vf^2=vi^2+2ad
d=vit+1/2at^2
vf=vi+at
d=vit-1/2at^2
d=vavt

The Attempt at a Solution


1. An object such as a ball let go by a person's hand falling vertically downward toward Earth has a velocity and acceleration vector in the same direction. An object such as a cannonball launched vertically upward will have a velocity vector upward and an acceleration vector down due to gravity which means the velocity and acceleration vectors are in opposite directions momentarily.

2. Both bullets hit the ground at the same time because both objects have the same initial velocity of zero and acceleration of gravity in the y-component. The x-component does not affect the y-component which is why it is ignored.

3. See attachment with no title.
4. The stone thrown downward will hit the ground first. Both stones hit the ground at the same speed.
5. 15^2+35^2=r^2
38m=r
The magnitude of the football's displacement is 38m.
6. vf=vi+at
vf=0-9.8(2.5)
vf=-24.5m/s
The velocity of the fish is 25m/s down at 2.5 seconds after being dropped.
b)d=vit-1/2at^2
d=0+4.9(2.5)^2
d=11.15m
The pelican was 11.15m above the water when it dropped the fish.
7. See attachment
Not sure how to do 8, 9 or 10.
 

Attachments

  • kinematics assignment 12.pdf
    40.7 KB · Views: 997
  • Untitled.png
    Untitled.png
    3.3 KB · Views: 530
Physics news on Phys.org
  • #2
Looking good on the first few. In #5, you didn't find the direction. In #6, you failed to use the initial upward velocity and in part (b) the time of fall was 10 s, not 2.5 s.
I didn't find you solution for #7.
#8 is a 2D vector problem. Sketch the velocity vectors for the wind and airspeed (placed head to tail). Their total must be in the eastward direction. From the sketch you could find the unknown angle with the Laws of sines and cosines or by splitting the vectors into horizontal and vertical parts.

#9 is similar - to velocity diagrams.
 
  • #3
Yup, all seems good... as delphi51 mentioned, remember to give a direction for the displacement vector in 5.
In 6, what is your argumant for using vi as 0? Do you not think it is traveling at the same speed as the pelican when released? rethink this one.
in #7 you can break up the components of in xy-axis format. The car is in linear motion up to the edge of the cliff so what parameter can be calculated for the vehicle at this point(end of cliff). take this parameter and break it into its x and y components and find the horizontal displacement seeing as you have the y displacement and use pathagoras to get the relative position. from here time could be calculated as well as final velocity, remember to give an angle to this as it is a vector. keep in mind, what is the vertical and horizontal acceleration of the vehicle after it left the cliff?
8 and 9 is as delphi51 stated.
#10... According to the projectile equations of motion:
Vi = sqrt((R^2g)/(Rsin2θ+2hcos^2θ))
where R is your launch range, h is the drop height from start point and θ is your launch angle which you have...

Hope you come right...
 
  • #4
Delphi51 said:
Looking good on the first few. In #5, you didn't find the direction. In #6, you failed to use the initial upward velocity and in part (b) the time of fall was 10 s, not 2.5 s.
I didn't find you solution for #7.
#8 is a 2D vector problem. Sketch the velocity vectors for the wind and airspeed (placed head to tail). Their total must be in the eastward direction. From the sketch you could find the unknown angle with the Laws of sines and cosines or by splitting the vectors into horizontal and vertical parts.

#9 is similar - to velocity diagrams.

Thanks Delphi51
 
  • #5
WillemBouwer said:
Yup, all seems good... as delphi51 mentioned, remember to give a direction for the displacement vector in 5.
In 6, what is your argumant for using vi as 0? Do you not think it is traveling at the same speed as the pelican when released? rethink this one.
in #7 you can break up the components of in xy-axis format. The car is in linear motion up to the edge of the cliff so what parameter can be calculated for the vehicle at this point(end of cliff). take this parameter and break it into its x and y components and find the horizontal displacement seeing as you have the y displacement and use pathagoras to get the relative position. from here time could be calculated as well as final velocity, remember to give an angle to this as it is a vector. keep in mind, what is the vertical and horizontal acceleration of the vehicle after it left the cliff?
8 and 9 is as delphi51 stated.
#10... According to the projectile equations of motion:
Vi = sqrt((R^2g)/(Rsin2θ+2hcos^2θ))
where R is your launch range, h is the drop height from start point and θ is your launch angle which you have...

Hope you come right...

Thanks WillemBouwer
 

What are the 5 most frequently asked questions about "Ten Kinematic Problems Grade 12 Physics"?

The top five most frequently asked questions about "Ten Kinematic Problems Grade 12 Physics" are:

1. What are kinematics and why is it important in physics?

Kinematics is the branch of physics that deals with the motion of objects without considering the forces that cause the motion. It is important in physics because it helps us understand and predict the behavior of objects in motion, which is essential in many real-world applications.

2. What are the different types of kinematic equations?

The most commonly used kinematic equations are the equations for displacement, velocity, and acceleration, which are d = vt, v = u + at, and v^2 = u^2 + 2ad, respectively. There are also equations for time, final velocity, and initial velocity.

3. How do I solve kinematic problems?

To solve kinematic problems, you need to identify the known and unknown variables, choose the appropriate kinematic equation, and plug in the values to solve for the unknown variable. It is also important to pay attention to units and use the correct formula for the given scenario.

4. How can I apply kinematics in real-life situations?

Kinematics is used in many real-life situations, such as calculating the speed and acceleration of vehicles, predicting the motion of projectiles, and understanding the motion of objects in sports. It is also used in engineering and design to analyze and improve the performance of machines and structures.

5. What are some common mistakes to avoid when solving kinematic problems?

Some common mistakes to avoid when solving kinematic problems include using the wrong formula, not converting units correctly, and not paying attention to the direction of motion. It is also important to double-check your calculations and use significant figures appropriately.

Similar threads

  • Introductory Physics Homework Help
Replies
12
Views
1K
  • Introductory Physics Homework Help
Replies
22
Views
287
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
11
Views
627
  • Introductory Physics Homework Help
Replies
28
Views
3K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
3K
Replies
5
Views
901
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
149
Back
Top