Physics energy questions

Question

1.What is the kinetic energy of a 69 N woman jogging at 0.77 m/s?

2.A car has 29,919 J of energy when moving down the street. The mass of the vehicle is 1,844 kg. What velocity is the car  moving at?

3.A 1,035 N rocket travels at constant speed for 1,643 m in 1.5 seconds. What is the kinetic energy of the rocket? 

*answer and explanation please*

Answer 1

(1)

K = kinetic energy

K = mv²/2

You have the weight in newtons. Divide it by g (= 9.8 m/s²) to get mass m in kg. You have v in meters/sec. Plug in the numbers for m and v, and get K in joules.

(2)

v = √(2K/m)

You have K in joules and m in kg. Plug in the numbers and get v in meters/sec.

(3)

Get the speed v by dividing travel distance by time, get mass by dividing the weight by g (as in problem (1)), and plug the numbers into

K = mv²/2

Answer 2

Use Kinetic Energy (E_K) = 1/2mv² for all these problems In question 1, the weight of the woman is given. Use F (the weight) = ma to calculate mass (a = g = 9.8 m/s²). For question 2 solve E_K = 1/2mv² for v and plug in the numbers. For question 3. Calculate velocity as distance/time and calculte mass as in question 1.

Answer 3

Use Kinetic Energy (E_K) = 1/2mv² for all these problems In question 1, the weight of the woman is given. Use F (the weight) = ma to calculate mass (a = g = 9.8 m/s²). For question 2 solve E_K = 1/2mv² for v and plug in the numbers. For question 3. Calculate velocity as distance/time and calculte mass as in question 1.