Answer:
Time needed: 2.5 s
Distance covered: 31.3 m
Explanation:
I'll start with the distance covered while decelerating. Since you know that the initial speed of the car is 15.0 m/s, and that its final speed must by 10.0 m/s, you can use the known acceleration to determine the distance covered by
v2f=v2i−2⋅a⋅d
Isolate d on one side of the equation and solve by plugging your values
d=v2i−v2f2a
d=(15.02−10.02)m2s−22⋅2.0ms−2
d=31.3 m
To get the time needed to reach this speed, i.e. 10.0 m/s, you can use the following equation
vf=vi−a⋅t, which will get you
t=vi−vfa
t=(15.0−10.0)ms2.0ms2=2.5 s
The answer is c. the force of his swing
At the time of the impact, there is a collision between two bodies moving in opposite directions.
The force exerted on the ball causes the change of velocity.
If "0.3 minute" is correct, then it's 9,543,272 Joules.
If it's supposed to say "0.3 SECOND", then the KE is 2,651 Joules.
