1. A spring or elastic can be stretched to store energy as it wants to return to rest.
2. Gravitational every can be is stored by moving a ball against gravity when lifted then released when bounced.
3. Separating two charged plates will store energy as the plates want to return to their original position.
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Answer:
the Princess in "St. George and the Dragon"
The gravitational force on the car is the force popularly known
as the car's "weight". Its magnitude is
(9.8 m/s²) times (the car's mass, in kilograms) .
The unit of this quantity is [newton] .
Answer:
79.2 m/s
Explanation:
θ = angle at which projectile is launched = 29.7 deg
a = initial speed of launch = 130 m/s
Consider the motion along the vertical direction
v₀ = initial velocity along the vertical direction = a Sinθ = 130 Sin29.7 = 64.4 m/s
y = vertical displacement = - 108 m
a = acceleration = - 9.8 m/s²
v = final speed as it strikes the ground
Using the kinematics equation
v² = v₀² + 2 a y
v² = 64.4² + 2 (-9.8) (-108)
v = 79.2 m/s
Answer:
The air resistance on the skydiver is 68.6 N
Explanation:
When the skydiver is falling down, there are two forces acting on him:
- The force of gravity, of magnitude 
, in the downward direction (where m is the mass of the skydiver and g is the acceleration due to gravity)
- The air resistance, 
, in the upward direction
So the net force on the skydiver is:
where
m = 7.0 kg is the mass
According to Newton's second law of motion, the net force on a body is equal to the product between its mass and its acceleration (a):
In this problem, however, the skydiver is moving with constant velocity, so his acceleration is zero:
Therefore the net force is zero:
And so, we have:
And so we can find the magnitude of the air resistance, which is equal to the force of gravity:
