Your teacher has given each lab group four liquids. Each liquid has been tinted using food coloring. Your teacher has asked you
2 answers:
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Answer:
2324 J
Explanation:
The formula for work is:
where is the force applied, and
is the distance moved, in this case
and we need to find
Since the crate is not moving up or down, we conclude that the <u>normal force must be equal to the weight </u>of the object:
where is the normal force and
is the weight, which is:
, where g is the gravitational acceleration
and
is the mass
.
---------
Thus the normal force is:
Now, the force due to the friction is defined as:
where is the coefficient of friction,
So, for the crate to move, the force applied must be equal to the frictional force:
And now that we know the force we can calculate the work:
substituting known values:
The force needed to the stop the car is -3.79 N.
Explanation:
The force required to stop the car should have equal magnitude as the force required to move the car but in opposite direction. This is in accordance with the Newton's third law of motion. Since, in the present problem, we know the kinetic energy and velocity of the moving car, we can determine the mass of the car from these two parameters.
So, here v = 30 m/s and k.E. = 3.6 × 10⁵ J, then mass will be
Now, we know that the work done by the brake to stop the car will be equal to the product of force to stop the car with the distance travelled by the car on applying the brake.Here it is said that the car travels 95 m after the brake has been applied. So with the help of work energy theorem,
Work done = Final kinetic energy - Initial kinetic energy
Work done = Force × Displacement
So, Force × Displacement = Final kinetic energy - Initial Kinetic energy.
Thus, the force needed to the stop the car is -3.79 N.