Finding Final Velocity by Energy Techniques

In summary, the conversation discusses finding the speed of a 1.50 kg snowball fired from a cliff with an initial velocity of 14.0 m/s and an angle of 41.0° above the horizontal. The energy equation of k1+u1=k2=u2 is used, but there is a mistake in solving for Vf. The correct answer should be 21.5 m/s. The person then asks GingerBread27 to check their private messages.
  • #1
GingerBread27
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A 1.50 kg snowball is fired from a cliff 13.5 m high with an initial velocity of 14.0 m/s, directed 41.0° above the horizontal.
(a) Using energy techniques, rather than techniques of Chapter 4, find the speed of the snowball as it reaches the ground below the cliff.
ok so I used the equation k1+u1=k2=u2
plugging in numbers i did 1/2(1.50kg)(14m/s)^2+(1.50kg)(9.8m/s^2)(13.5m)=1/2(1.50kg)(vf)^2+(1.50kg)(9.8m/s)(0). Then I solve for Vf and I get a wrong answer. Now i realize this is probably wrong since I haven't incorporated the angle, but I'm not sure. Any ideas?
 
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  • #2
Well. The technique is right, so you must've made some silly error in solving for Vf.
What answer did you get? It should be 21.5 m/s.
 
  • #3
Yeah 21.5 is the answer, guess I must have made a mistake with the calculator :blushing: . Thank You :smile:
 
  • #4
Hey GingerBread27 please check your private messages...thanks!
 
  • #5
GingerBread27 check your private messages 1 more time...thanks
 

1. How do energy techniques help in finding final velocity?

Energy techniques, such as the conservation of energy principle, can be used to determine the final velocity of an object by considering the initial energy and the energy at the final state. This allows for a more direct and efficient approach to solving for final velocity without having to consider other factors such as acceleration or time.

2. What is the formula for finding final velocity using energy techniques?

The formula for finding final velocity using energy techniques is: Vf = √(2Ef/m), where Vf is the final velocity, Ef is the final energy, and m is the mass of the object.

3. Can energy techniques be used for all types of objects?

Energy techniques can be used for any object that is subject to conservative forces, meaning that the total mechanical energy of the object is conserved. This includes objects moving in a straight line, rotating objects, and objects undergoing simple harmonic motion.

4. What are the advantages of using energy techniques to find final velocity?

One advantage of using energy techniques is that it eliminates the need to consider factors such as acceleration and time, which can be difficult to measure accurately. It also provides a more direct and efficient approach to solving for final velocity, making it a useful tool for problem solving in physics.

5. Are there any limitations to using energy techniques for finding final velocity?

Energy techniques may not be applicable in situations where non-conservative forces, such as friction or air resistance, are present. In these cases, the total mechanical energy of the object is not conserved and the final velocity cannot be determined using energy techniques alone. Other methods, such as kinematic equations, may need to be used in conjunction with energy techniques to find the final velocity.

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