Bob gained (80lbs x 14ft) = 1120 ft-lbs of energy.
Fred gained (110lbs x 14ft) = 1540 ft-lbs of energy
Since they both took the same amount of time, Fred's power (rate
of doing work) was greater than Bob's power (rate of doing work).
Answer:
The speed of the plank is 81.68 m/s
Explanation:
Given that,
Speed of bullet = 152 m/s
Speed of wood = 128 m/s
Speed of another bullet = 97 m/s
We need to calculate the speed of plank
Using conservation of momentum
Where,
u = initial velocity
v = final velocity
....(I)
....(II)
From equation(I) and equation(II)
Hence, The speed of the plank is 81.68 m/s
Answer:
Explanation:
The drawing is missing but we can still answer.
In fact, for a stone being whirled on a tabletop, the tension in the cord provides the centripetal force that keeps the stone in circular motion; therefore we can write:
where
T is the tension
m is the mass of the stone
v is the speed
r is the radius of the circle
For the first stone, we have
(1)
While for the second stone,
(2)
since m and v are identical for the two stones. We know that the first cord is longer, such that the radius of the circle in the 1st case is twice that of the second case:
So, substituting into (1),
which means that the tension in the longer cord is half the tension in the shorter cord.
Answer:
One coulomb (C) of charge represents an excess or deficit of 6.24 x 1018 electrons
Explanation:
Answer:
a) 0.32 m b) -2.4 m c) 1.08 m/s d) -4 m/s
Explanation:
a)
- As the x and y axes (as chosen) are perpendicular each other, the movements along these axes are independent each other.
- This means that we can use the kinematic equations for displacements along both axes.
- In the x direction, as the only initial velocity is in the south direction (-y axis), the skateboarder is at rest, so we can write:
- In the y-direction, as no acceleration is acting on the skateboarder, we can write the following displacement equation:
- For t = 0.6s, replacing by the givens, we get the position (displacement from the origin) on the x-axis, as follows:
b)
- From (2) we can get the position on the y-axis (displacement from the origin) as follows:
c)
- In the x- direction, we can find the component of the velocity along this direction, as follows:
- Replacing by the values, we have:
d)
- As the skateboarder moves along the y-axis at a constant speed equal to her initial velocity, we have:
vfy = voy = -4 m/s