Question #7024c

1 Answer
Junaid Mirza
Nov 12, 2017

#"8 m/s"#

Explanation:

#K = 1/2mv^2#

From above,

#v ∝ sqrt(K)#

#v_2/v_1 = sqrt(K_2/K_1)#

Subtract 1 from both the sides

#v_2/v_1 - 1 = sqrt(K_2/K_1) - 1#

#(v_2 - v_1)/v_1 = sqrt(K_2/K_1) - 1#

#("4 m/s")/v_1 = sqrt((100 + 125) / 100) - 1#

#("4 m/s")/v_1 = 15/10 - 1#

#("4 m/s")/v_1 = 5/10#

#v_1 = ("4 m/s × 10")/5 = "8 m/s"#

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