John does 3.2J of work to lower the window shade in her bedroom a distance of 0.8m. How much force must John exert on the window
1 answer:
Answer:
Explanation:
Work is energy transferred when an object is moved. It is the product of force and distance.
John did 3.2 Joules of work or 3.2 Newton meters of work (the units are equivalent). The window shade was lowered a distance of 0.8 meters.
- W=3.2 N*m
- d= 0.8 m
Substitute the values into the formula.
We are solving for the force, so we must isolate the variable F. It is being multiplied by 0.8 meters. The inverse operation of multiplication is division, so divide both sides of the equation by 0.8 m.
The units of meters cancel.
John must exert <u>4 Newtons of force.</u>
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Answer:
The total distance is 130.2 [m]
Explanation:
In order to solve this problem we must use the expressions of kinematics. The clue to solve this problem is that the cart starts from rest, i.e. its initial speed is zero.
where:
Vf = final velocity [m/s]
Vo = initial velocity = 0
a = acceleration = 3 [m/s²]
t = time = 8[s]
Vf = 0 + (3*8)
Vf = 24 [m/s]
With this velocity we can calculate the displacement using the following expression.
where
x = distance traveled [m]
24² = 0 + (2*3*x)
x = 576/(6)
x = 96 [m]
Note: The positive sign in the equations is because the car is accelerating, it means its velocity is increasing.
The other important clue to solve this problem in the second part is that the final velocity is now the initial velocity.
We must calculate the final velocity.
Vf = final velocity [m/s]
Vi = initial velocity = 24 [m/s]
a = desacceleration = 1.6 [m/s²]
t = time = 15 [s]
Vf = 24 - (1.6*15)
Vf = 21.6 [m/s]
With this velocity, we can calculate the displacement using the following expression.
where
x = distance traveled [m]
21.6² = 24² - (2*1.6*x)
x = 109.44/(3.2)
x = 34.2 [m]
Note: The negative sign in the equations is because the car is desaccelerating, it means its velocity is decreasing.
Therefore the total distance is Xt = 34.2 + 96 = 130.2 [m].
Good morning.
We have:
Where j is the unitary vector in the direction of the y-axis.
We have that
We add the vector -a to both sides:
Therefore, the magnitude of b is 47 units.
We have:
Where j is the unitary vector in the direction of the y-axis.
We have that
We add the vector -a to both sides:
Therefore, the magnitude of b is 47 units.