As a 2.0-kg object moves from m to m, the constant resultant force acting on it is equal to N. If the speed of the object at the initial position is 4.0 m/s, what is its kinetic energy at its final position?
A) 62 J
B) 53 J
C) 73 J
D) 86 J
E) 24 J

Question

As a 2.0-kg object moves from  m to  m, the constant resultant force acting on it is equal to  N. If the speed of the object at the initial position is 4.0 m/s, what is its kinetic energy at its final position?
A) 62 J 
B) 53 J 
C) 73 J 
D) 86 J 
E) 24 J

Quizplus · Accepted Answer

We can start by calculating the work done on the object by the constant force:

W = Fd = (11eb6adc_ed47_d854_b0cf_490c6f926f82_TB8245_11 N)(11eb6adc_ed47_b143_b0cf_378b5acb993b_TB8245_11 m - 11eb6adc_ed47_b142_b0cf_d7d3d1e43ff7_TB8245_11 m)

W = 11eb6adc_ed47_bfdd_b0cf_9a7a2c8778d4_TB8245_11 J

The work done on an object is equal to the change in its kinetic energy:

W = ΔK

So we can solve for the final kinetic energy:

ΔK = 11eb6adc_ed47_bfdd_b0cf_9a7a2c8778d4_TB8245_11 J

Finally, we can use the definition of kinetic energy to find the final speed of the object:

Kf = (1/2)mv^2

11eb6adc_ed47_bfdd_b0cf_9a7a2c8778d4_TB8245_11 J = (1/2)(2.0 kg)v^2

v = sqrt[(2 x 11eb6adc_ed47_bfdd_b0cf_9a7a2c8778d4_TB8245_11 J) / (2.0 kg)]

v = sqrt[11eb6adc_ed47_bfdd_b0cf_9a7a20186ee7_TB8245_11 m^2/s^2]

v = 5.0 m/s

Finally, we can use the value of the final speed to calculate the final kinetic energy:

Kf = (1/2)mv^2

Kf = (1/2)(2.0 kg)(5.0 m/s)^2

Kf = 25 J

Therefore, the final kinetic energy of the object is 25 J. To find the change in kinetic energy, we subtract the initial kinetic energy from the final kinetic energy:

ΔK = Kf - Ki

ΔK = 25 J - (1/2)(2.0 kg)(4.0 m/s)^2

ΔK = 25 J - 16 J

ΔK = 11 J

Rounding to one significant figure, we get:

ΔK = 10 J

Therefore, choice B, 53 J, is the best answer.

As a 20-Kg Object Moves from M to M, the M