Question

4. A truck has four times the mass of a car and is moving with twice the speed of the car.
If KE, and KE, refer to the kinetic energies of truck and car respectively, it is correct to say
that: (KE = 72 my?)

Answer 1

Answer:

Relation between kinetic energy of truck and kinetic energy of car is given as

$K_t = 16 K_c$

Explanation:

As we know that mass of truck is four times the mass of car

$m_t = 4 m_c$

and the speed of truck is double that of speed of car

$v_t = 2v_c$

now we have kinetic energy of the truck is given as

$K_t = \frac{1}{2}m_t v_t^2$

similarly kinetic energy of car is given as

$K_c = \frac{1}{2}m_cv_c^2$

now from above two equations we have

$\frac{K_t}{K_c} = \frac{\frac{1}{2}m_tv_t^2}{\frac{1}{2}m_cv_c^2}$

$\frac{K_t}{K_c} = 4(4) = 16$

so we have

$K_t = 16 K_c$