d thought i wouldnt trust me on it
As our story begins, the sled ... whose mass is 8 kg ... is sliding along the ice at a speed of 4 m/s.
The sled's kinetic energy is (1/2 m v²) = (4 kg · 16 m²/s²) = 64 J .
After what seems like only the blink of an eye, the sled is no longer sliding. It is stationary. Motionless. At Rest. Just sitting there !
Its speed has been reduced to zero and ... because kinetic energy is the energy of motion ... the sled's kinetic energy is now also zero. Sixty-four Joules of energy have disappeared !
How can this be ? ! ? We know that energy is conserved. It can never just appear out of nothing, and it can never just disappear into nothing. If energy suddenly appears, it had to come from somewhere, and if energy suddenly disappears, it had to go somewhere. So where did our 64 Joules of kinetic energy go ?
It went into the ice, THAT's where ! We can say that the sled did 64J of work, and melted a thin slick layer of water on the surface of the ice. OR we can say that friction did NEGATIVE 64J of work on the sled, to cancel the 64J that it had originally, sap its kinetic energy, and bring it to rest.
I think <em>choice-B</em> was supposed to say "<em>B. -64J</em>", but somebody typed it sloppily and neglected to proofread it before posting.
The stopping distance is 143.1 m
Explanation:
First of all, we have to find the acceleration of the hockey puck. This can be done by using Newton's second law of motion:
where
is the net force acting on the puck (the force of friction, negative because it acts in a direction opposite to the direction of motion)
m = 0.12 kg is the mass of the puck
a is the acceleration
Solving for a,
The motion of the puck is a uniformly accelerated motion, therefore we can use the following suvat equation:
where:
v = 0 is the final velocity (the puck comes to a stop)
u = 18.3 m/s is the initial velocity
is the acceleration
s is the stopping distance
And solving for s, we find
Learn more about accelerated motion:
brainly.com/question/9527152
brainly.com/question/11181826
brainly.com/question/2506873
brainly.com/question/2562700
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