Answer:
W= 38.4 J
Explanation:
Given that
m = 80 g= 0.08 kg
Initial speed ,u= 22 m/s
Final speed ,v= 38 m/s
The change in the kinetic energy of the particle


ΔKE= 38.4 J
We know that
Work done by all the forces =Change in the kinetic energy
That is why net work done = 38.4 J.
W= 38.4 J
Therefore the answer will be 38.4 J.
Answer:

Explanation:
The initial mechanical energy of the object, when it is located at height h above the the planet, is just gravitational potential energy:

where
G is the gravitational constant
M is the mass of the planet
m is the mass of the object
R is the radius of the planet
h is the altitude of the object
When the object hits the ground, its mechanical energy will sum of potential energy and kinetic energy:

where
v is the speed of the object at the ground
Since the mechanical energy is conserved, we can write

and solving for v, we find

Answer:
Last statement option: "The acceleration after it leaves the hand is 10 m/s/s downwards."
Explanation:
At every instant of its motion, the ball is under the effects of the acceleration due to gravity (assumed to be 10 m/s^2). This is true at whatever altitude the ball is. The acceleration due to gravity is always pointing down (not up).
In the absence of air resistance, the motion is described kinematically by a parabola with the branches pointing down as a function of time (motion under constant acceleration), with the vertex indicating the maximum altitude the ball reaches. Both branches (representing motion upwards and downwards) are equidistant from the vertex, so the time going up equals the time coming down.
Therefore, the only statement option that is correct is the last one: "The acceleration after it leaves the hand is 10 m/s/s downwards."
Answer:
The total resistance decreases
Explanation:
The total resistance of a parallel circuit is given by:

where R1, R2, etc. are the individual resistances.
We notice that if we add one more resistor in parallel, we add another positive term
to the sum, therefore the term
increases. However, this term is the reciprocal of the total resistance: therefore, this means that the total resistance will decrease.
Answer:
The angular momentum of the wheel is
.
Explanation:
It is given that,
Mass of the wheel, m = 2.73 kg
Radius of the wheel, r = 31 cm = 0.31 m
Angular speed of the wheel, 
We need to find its angular momentum. It is given by :

I is the moment of inertia of the wheel, 



So, the angular momentum of the wheel is
. Hence, this is the required solution.