I think it’s 10 kg since 20/2=10
He is American. Alex Rodriguez
Answer:
1800J
Explanation:
Step one:
given data
mass of bullet m= 3g= 0.03kg
initial velocity u = 400m/s
final velocity v= 200 m/s
Step two:
1.The bullet's lost kinetic energy went inside the tree.
2. The energy transferred is computed as
= initial KE- KE final
Initial KE= 1/2mu^2
Initial KE= 1/2*0.03*400^2
Initial KE= 1/2*0.03*160000
Initial KE= 1/2*4800
Initial KE= 2400J
KE final= 1/2mv^2
KE final= 1/2*0.03*200^2
KE final= 1/2*0.03*40000
KE final= 1/2*1200
KE final= 600J
KE transferred = 2400-600
KE transferred= 1800J
Answer:
a. 125 kJ
Explanation:
Her total energy is the same as the potential energy she had at the top of the hill:
PE = mgh
= (52 kg)(9.8 m/s^2)(245 m) = 124,852 J
≈ 125 kJ . . . . matches choice A
_____
After skiing down 112 m, some of her initial energy is converted to kinetic energy, and some remains as potential energy. We assume the ski slope is essentially frictionless, and air resistance is negligible.
