Questions related to Kinematics

  • Thread starter alexandria
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    Kinematics
In summary, the truck traveled 14.0 km (South) in 15 min, then traveled another 6 km at a slower pace over 10 min, staying at this location for 5 min. The truck continued on at a constant speed for another 8 km towards the destination, taking 15 min for this portion of its journey.
  • #1
alexandria
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Member reminded that separate problems should be given separate threads.

Homework Statement


so I am sending my unit in for marking, and i collected a bunch of kinematic related questions that I've attempted to answer, but don't know if I am on the right track. Any help would be appreciated. Thanks.
1.[/B]
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2.
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3.
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4.
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5.
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Homework Equations


relevant equations are listed with each question

The Attempt at a Solution



1.
The truck traveled 14.0 km (South) in 15 min. The truck continued another 6 km at a slower pace over 10 min, and then stayed at this location for 5 min. The truck continued on at a constant speed for another 8 km towards the destination, taking 15 min for this portion of its journey.

2.
Displacement = 131 km (South)

Average velocity = total displacement / total time

Average velocity = 131 km (S) / 2.0 h

Average velocity = 65.5 km /h (south)

3.
a)

d = v x t

Time to cross river:

t = d / v

= 0.032 km / 2.5 km/h

= 0.0128 hrs

Walking distance:

d = (1.2 km/h) x (0.0128 hrs)

d = 0.01536 km = 15.36 m

Sandra will have to walk 15.36 m to reach the farmer’s market.

b)
Time it takes to cross the river:

t = d / v

t = 32.0 m (E) / 0.69 m/s (E)

t = 46 s

Time it takes to walk the riverbank:

t = d / v

t = 15.36 m / 0.72 m/s

t = 21 s

Walking to the farmer’s market will result in the shortest time for Sandra to reach her destination.

4.
Increase the launch angle above 45 degrees, to reduce the horizontal displacement. This way the water balloon will hit the target instead of passing it.

5.
is it because the supplies will be blown off course??
 

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  • #2
alexandria said:
The truck continued another 6 km at a slower pace over 10 min
Are you sure it 'continued' in the same direction? What does the fact that the North-South coordinate is reducing over this 10 minutes tell us?
alexandria said:
The truck continued on at a constant speed for another 8 km towards the destination
Towards the destination? What do you mean by the destination? A place to deliver cabbages, or the home depot?
 
  • #4
ok sorry about that :P
"Are you sure it 'continued' in the same direction? What does the fact that the North-South coordinate is reducing over this 10 minutes tell us?"
is the truck now traveling in an east-south direction?
 
  • #5
alexandria said:
is the truck now traveling in an east-south direction?
We are given no information about its East-West coordinates. Only the North-South coordinates are given. Hence we should assume that it is traveling only along a road that runs North-South.
 
  • #6
so was the truck traveling North initially, but then began to travel towards the south direction?
 
  • #7
No, traveling South first, because the coordinate given is the km to the South. THen turns and travels North later.
 
  • #8
alexandria said:
so was the truck traveling North initially, but then began to travel towards the south direction?
Nearly right. That might not be what you intended to say.
 
  • #9
so is this how it goes:
The truck traveled 14.0 km (South) in 15 min. The truck then traveled another 6 km North at a slower pace over 10 min, staying at this location for 5 min. The truck continued on at a constant speed for another 8 km towards the destination, taking 15 min for this portion of its journey.

also am i right that the truck continues at a constant speed?
 
  • #10
alexandria said:
so is this how it goes:
The truck traveled 14.0 km (South) in 15 min. The truck then traveled another 6 km North at a slower pace over 10 min, staying at this location for 5 min. The truck continued on at a constant speed for another 8 km towards the destination, taking 15 min for this portion of its journey.

also am i right that the truck continues at a constant speed?
Yes, but as has already been suggested you should state the speeds.
 
  • #11
oh ok, but I am following the example in my lesson, so in that context do you think my answer is valid.
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  • #12
alexandria said:
oh ok, but I am following the example in my lesson, so in that context do you think my answer is valid.
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If that's the example to be followed then not mentioning the actual speeds is fine.
 
  • #13
ok thank you for your help.
 

Related to Questions related to Kinematics

1. What is kinematics?

Kinematics is the branch of physics that studies the motion of objects without considering the causes of the motion. It involves the concepts of position, velocity, and acceleration.

2. What are the three basic types of motion in kinematics?

The three basic types of motion in kinematics are translational motion, rotational motion, and vibrational motion. Translational motion is when an object moves along a straight line, rotational motion is when an object rotates around an axis, and vibrational motion is when an object oscillates back and forth.

3. How is velocity different from speed in kinematics?

Velocity is a vector quantity that describes both the speed and direction of motion, while speed is a scalar quantity that only describes how fast an object is moving without considering direction.

4. What is the difference between distance and displacement in kinematics?

Distance is the total length traveled by an object, while displacement is the shortest distance between the starting and ending position of an object. Displacement takes into account the direction of motion, while distance does not.

5. How is acceleration calculated in kinematics?

Acceleration is calculated by dividing the change in velocity by the change in time. It is a measure of how quickly an object's velocity is changing, either by increasing or decreasing in magnitude or changing direction.

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