Okay the equation for kinetic energy is = 1/2mv^2 so how would i figure this out??

If a semi-truck decreases its speed from 10 m/s to 5 m/s, its new Kinetic Energy is:

a)4 times its old Kinetic Energy
b)2 times its old Kinetic Energy
c)1/2 its old Kinetic Energy
d)1/4 its old Kinetic Energy
okay since the v is half of what it was would it be c????

because v is the only thing changing the value of m is not relevant. to find out what would happen to the energy we compare the differences in v

ie 10^2 = 100
5^2 = 25
since the new v value is a quarter of the previous value the answer is (d)

alternatively, your reasoning before is correct but you have forgotten that the v value is squared ie 0.5^2 = 0.25

To solve this question, we can use the equation for kinetic energy: KE = 1/2mv^2. In this equation, m represents the mass of the object and v represents its velocity.

The question states that the semi-truck decreases its speed from 10 m/s to 5 m/s, so we need to compare the kinetic energy before and after the decrease in speed.

Let's assume the mass of the semi-truck remains constant. So, m (mass) can be canceled out from the equation.

Now, let's calculate the initial kinetic energy:
KE_initial = 1/2 * m * (10 m/s)^2

And the final (new) kinetic energy:
KE_final = 1/2 * m * (5 m/s)^2

Now we can compare the initial and final kinetic energy values to determine which option is correct.

Let's calculate the ratio between the final and initial kinetic energy:
KE_final / KE_initial = [1/2 * m * (5 m/s)^2] / [1/2 * m * (10 m/s)^2]
= (5 m/s)^2 / (10 m/s)^2
= 25 / 100
= 1/4

Therefore, the ratio of the final kinetic energy to the initial kinetic energy is 1/4 or 1:4.

Hence, the correct answer is option (d) - The new Kinetic Energy is 1/4 its old Kinetic Energy.