# physics

A father racing his son has half the kinetic energy of the son, who has half the mass of the father. The father speeds up by 1 m/s and then has the same kinetic energy as the son. What are the original speeds a) of the father? b) of the son?

I know that KE=1 for the son and he has 1/2mass. The father has 1/2 KE and 1 mass. Should I use v^2=V_i^2 +2ad?
How would I do this?

Let V be the initial velocity of the son, and M be his mass The father's initial speed must be V/2, so that
(KE)son = (1/2) M V^2
(KE)father = (1/2)*(2M)*(V/2)^2
= (1/2)(KE)son
You also know that
(1/2)(2M)[(V/2) +1]^2= (1/2) M V^2
2M [(V/2) +1]^2 = MV^2
2[(V/2) +1]^2 = V^2
This will lead to a quadratic equation for V. Solve for V, and then V/2, the father's initial speed.

1. 👍 0
2. 👎 0
3. 👁 157
1. 1/Root2minus 1

1. 👍 0
2. 👎 0
posted by sisay

## Similar Questions

1. ### Physics

A father racing his son has one-third the kinetic energy of the son, who has two-fifths the mass of the father. The father speeds up by 2.5 m/s and then has the same kinetic energy as the son.

asked by Sam on October 28, 2010
2. ### Physics Concepts

A father racing his son has one-third the kinetic energy of the son, who has two-fifths the mass of the father. The father speeds up by 1.5 m/s and then has the same kinetic energy as the son. What is the Father's initial speed?

asked by Bill on March 5, 2011
3. ### physics

A father racing his son has 1/3 the kinetic energy of the son, who has 1/3 the mass of the father. The father speeds up by 1.4 m/s and then has the same kinetic energy as the son. What are the original speeds of (a) the father and

asked by nan on October 3, 2011
4. ### physics

A father racing his son has 1/3 the kinetic energy of the son, who has 1/4 the mass of the father. The father speeds up by 1.8 m/s and then has the same kinetic energy as the son. What are the original speeds of (a) the father and

asked by wee on November 18, 2013
5. ### logic

A son and his father take a daily walk up a hill. It is 1.5 km to the top of the hill. As the father gets older he can only walk half the speed of his son. So they start together but the father trails his son. The father reaches

asked by Dell on December 1, 2011
6. ### NEED HELP...how do i draw a visual for this ques?

A son and his father take a daily walk up a hill. It is 1.5 km to the top of the hill. As the father gets older he can only walk half the speed of his son. So they start together but the father trails his son. The father reaches

asked by Dell on December 6, 2011
7. ### College Math

A certain man spent 10% of his life in childhood and 20% of his life as a young adult at which time he married his lovely bride. Five years later his son was born. His son lived to be half the age of his father when his father

asked by Jess on September 29, 2008
8. ### Spanish

How do you tell time in Spanish. son las 5 ye 2 en canada!no se como pero en todo lugar es different! yo so que no puedo escribe muy bein en espanol pero me gusta! adios! Dios te bendiga! Thank you for using the Jiskha Homework

asked by ANA on November 9, 2006
9. ### English

Please check my answer. I'm not sure which is right because I'm pretty sure every father feels the need to do all of the below. Read the following sentence from "No Dogs Bark." "I'll get you to Tonaya. There I'll find somebody to

asked by jaycee on September 15, 2014
10. ### Concept of Ration

A father distrubes R500.00 between his three sons that the eldest son gets twice as much as the second son, who in turn, gets as much as the youngest son. Using the Concept of Ratio, determine the amount that each son gets

asked by TL Matabane on April 28, 2010

More Similar Questions