Question

Roberto has twice the mass his sister Mary has (see above) but runs at the same velocity as Mary. Will his kinetic energy be twice as much? Show your work. What happens to Roberto’s kinetic energy when he runs twice as fast?

Answer 1

Answer:

one sec

Explanation:

Answer 2

Answer:

yes Robert's kinetic energy will be twice as much

if Robert runs twice as fast, then his KE will be 8 times Mary's KE

Explanation:

Kinetic energy KE = $\frac{1}{2}$m$v^{2}$

for Robert KE =  $\frac{1}{2}$(2m)$v^{2}$ =  m$v^{2}$

for Mary KE = $\frac{1}{2}$m$v^{2}$

If you divide Robert KE by Mary KE = m$v^{2}$ /  $\frac{1}{2}$m$v^{2}$ = 2; yes Robert's kinetic energy will be twice as much

if Robert v is equal to 2v

for Robert KE =  $\frac{1}{2}$(2m)$(2v)^{2}$ =  4m$v^{2}$

for Mary KE = $\frac{1}{2}$m$v^{2}$

If you divide Robert new KE by Mary's KE = 4m$v^{2}$ /  $\frac{1}{2}$m$v^{2}$ = 8, if Robert runs twice as fast, then his KE will be 8 times Mary's KE