a The kinetic energy of an object always has a positive value.
Explanation:
The kinetic energy of an object is the energy possessed by an object due to its motion, and it can be calculated as
where
m is the mass of the object
v is its speed
Let's now analyze each statement:
a The kinetic energy of an object always has a positive value. --> TRUE. In fact, the mass of the object is always positive, and the term is always positive as well, so the kinetic energy is always positive.
b The kinetic energy of an object is directly proportional to its speed. --> FALSE. Looking at the formula, we see that the kinetic energy is proportional to the square of the speed, .
c The kinetic energy of an object is expressed in watts. --> FALSE. Watts is the units for measuring power, while the kinetic energy is measured in Joules, the units for the energy.
d The kinetic energy of an object is a quantitative measure of its inertia. --> FALSE. The inertia of an object depends only on its mass, not on its speed.
e The kinetic energy of an object is always equal to the object’s potential energy. --> FALSE. The potential energy depends on the altitude from the ground, not from the speed, so the two energies can be different.
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Answer:
The car strikes the tree with a final speed of 4.165 m/s
The acceleration need to be of -5.19 m/seg2 to avoid collision by 0.5m
Explanation:
First we need to calculate the initial speed
Once we have the initial speed, we can isolate the final speed from following equation:
Then we can calculate the aceleration where the car stops 0.5 m before striking the tree.
To do that, we replace 62 m in the first formula, as follows:
Answer:
please read the answer below
Explanation:
The angular momentum is given by
By taking into account the angles between the vectors r and v in each case we obtain:
a)
v=(2,0)
r=(0,1)
angle = 90°
b)
r=(0,-1)
angle = 90°
c)
r=(1,0)
angle = 0°
r and v are parallel
L = 0kgm/s
d)
r=(-1,0)
angle = 180°
r and v are parallel
L = 0kgm/s
e)
r=(1,1)
angle = 45°
f)
r=(-1,1)
angle = 45°
the same as e):
L = 5kgm/s
g)
r=(-1,-1)
angle = 135°
h)
r=(1,-1)
angle = 135°
the same as g):
L = 5kgm/s
hope this helps!!
Answer:
Explanation:
Expression for escape velocity
ve =
ve² R / 2 = GM
M is mass of the planet , R is radius of the planet .
At distance r >> R , potential energy of object
=
Since the object is at rest at that point , kinetic energy will be zero .
Total mechanical energy = + 0 =
Putting the value of GM = ve² R / 2
Total mechanical energy = ve² Rm / 2 r
This mechanical energy will be conserved while falling down on the earth due to law of conservation of mechanical energy . So at surface of the earth , total mechanical energy
= ve² Rm / 2 r