Some Kinematics questions with cars and satallites

In summary, the conversation involved difficulty with calculating a collision between a car and a truck, due to the standard equation not applying. The question also included finding the velocity immediately after impact. A suggestion was given to use conservation of momentum in two dimensions. The conversation also touched on questions about an Earth satellite's acceleration and the mass of the Earth, with the formula for acceleration in a circular orbit mentioned.
  • #1
neonjr
6
0
Having difficulty with the followingCalculating this collision, as the standard equation does not apply, i don't think.

Question 1:

A 2000kg car traveling at 24 m/s EAST (x), collides with a 3600kg truck traveling at 10m/s SOUTH(y). What is there velocity immediately after impact.

Question 2:

An Earth Satellite travels in a circular orbit of radius 4 times the Earths radius. Calculate its acceleration in m/s^2


Question 3:

A satellite circles the Earth at an average altitude of 760km, with a period of 100 min. Calculate the mass of the Earth, if G = 6.67x10^-11 Nm^2/kg^2, and the radius of the Earth is 6.38x10^6m.


Can you advise me the correct equation to use and directions, I'm lost. Please and thank you.

Josh
 
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  • #2
Welcome to PF!

neonjr said:
Having difficulty with the followingCalculating this collision, as the standard equation does not apply, i don't think.
A 2000kg car traveling at 24 m/s EAST (x), collides with a 3600kg truck traveling at 10m/s SOUTH(y). What is there velocity immediately after impact.

Hi Josh! Welcome to PF! :smile:

By "standard equation", I take it you mean conservation of momentum in one dimension?

It's ok - you just have two equations instead of one - conservation of momentum North, and conservation of momentum East! :smile:

(btw, I suppose you're expected to use conservation of energy as well - but in practice, it wouldn't be conserved, because the vehicles would be deformed in the collision. :frown:)

As to Questions 2 and 3: do you know a formula for the aceleration of something in a circle?
 
  • #3




For question 1, we can use the conservation of momentum equation to calculate the velocity after the collision. The equation is: m1v1 + m2v2 = (m1 + m2)v3, where m1 and m2 are the masses of the car and truck respectively, v1 and v2 are their velocities before the collision, and v3 is their velocity after the collision. We can plug in the values and solve for v3. Remember to take into account the direction of the velocities.

For question 2, we can use the equation for centripetal acceleration, which is a = v^2/r, where v is the velocity and r is the radius of the circular orbit. The velocity of the satellite can be calculated using the equation v = 2πr/T, where T is the period of the orbit. Plug in the values and solve for a.

For question 3, we can use the equation for centripetal force, which is F = (mv^2)/r, where m is the mass of the satellite, v is its velocity, and r is the radius of the orbit. We can also use the equation for gravitational force, which is F = (Gm1m2)/r^2, where G is the gravitational constant, m1 and m2 are the masses of the Earth and the satellite respectively, and r is the radius of the Earth. Set these two equations equal to each other and solve for the mass of the Earth, m1.

Remember to always pay attention to the units and directions when solving kinematics problems. I recommend practicing with similar problems and using online resources or textbooks to review the equations and concepts. Good luck!
 

1. How do cars and satellites use kinematics?

Cars and satellites use kinematics to describe and analyze the motion of objects. Kinematics involves the study of position, velocity, and acceleration without considering the forces acting on the object.

2. What is the difference between linear and angular kinematics?

Linear kinematics deals with the motion of objects in a straight line, while angular kinematics deals with the motion of objects in a circular path. Both involve the same concepts of position, velocity, and acceleration, but the calculations and equations are slightly different.

3. How does the speed of a car affect its stopping distance?

The speed of a car directly affects its stopping distance. The higher the speed, the longer the stopping distance will be. This is because the car has more kinetic energy at higher speeds, so it takes longer to come to a complete stop.

4. Why do satellites orbit the Earth instead of falling to the ground?

Satellites orbit the Earth because of the balance between their forward motion and the pull of gravity. The Earth's gravity pulls the satellite towards it, but the satellite's forward motion keeps it from falling to the ground. This results in a circular orbit around the Earth.

5. How does the mass of a car affect its acceleration?

The mass of a car does affect its acceleration. The larger the mass of the car, the more force is needed to accelerate it. This is because of Newton's Second Law, which states that the acceleration of an object is directly proportional to the force applied and inversely proportional to the mass of the object.

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