Acceleration = (change in speed) / (time for the change)
Change in speed = (speed at the end) minus (speed at the beginning.
The cart's acceleration is
(0 - 2 m/s) / (0.3 sec)
= ( -2 / 0.3 ) (m/s²) = -(6 and 2/3) m/s² .
Newton's second law of motion says
Force = (mass) x (acceleration) .
For this cart: Force = (1.5 kg) x ( - 6-2/3 m/s²)
= ( - 1.5 x 20/3 ) (kg-m/s²)
<span> = </span>- 10 newtons .
<span>The force is negative because it acts opposite to the direction </span>
<span>in which the cart is moving, it causes a negative acceleration, </span>
<span>and it eventually stops the cart.</span>
Answer:
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If the floor is truly frictionless, then ANY force, no matter how small, applied for
ANY time, no matter how short, will set the block in motion. The force can then
be taken away, because on a frictionless surface, NO force is required in order
to keep the block moving.
The work done is equal to the kinetic energy you want the block to have. That
can be as much or as little as you feel like giving it.
From the basic "heat lost by hot object=heat gained by colder object" principle, we have
m1c1ΔT1=m2c2ΔT2
where m1= 1kg
m2=4kg
c1=900J/kg k
c2=4200J/kg k
With this information at hand we have
m1c1(90-T)=m2c2(T-25)
after substituting the given values we can find that
T=28.3^{0}c