Answer:
The Mass of a person is calculated to be 28.6kg .
Explanation:
This is based on Kinetic energy and we know, that Kinetic energy is the energy possessed by body by virtue of its motion .
It can be calculated by expression :
K.E=1/2mv²
Velocity of a person = 11.2m/sec
Kinetic energy = 1800J
Mass of person = ?
We know ,
K.E=1/2mv²
so, putting values we have :
1800=1/2 x m x (11.2)²
That is ,
m=1800 x 2 /11.2 x 11.2
or
m=3600/125.44
m = 28.6 kg
We can solve the problem by using conservation of momentum.
The player + ball system is an isolated system (there is no net force on it), therefore the total momentum must be conserved. Assuming the player is initially at rest with the ball, the total initial momentum is zero:

The total final momentum is:

where
is the momentum of the player and
is the momentum of the ball.
The momentum of the ball is: 
While the momentum of the player is:
, where M=59 kg is the player's mass and vp is his velocity. Since momentum must be conserved,

so we can write

and we find

and the negative sign means that it is in the opposite direction of the ball.
By definition, the work done by a force is given by:

Where,
F: magnitude of force
d: distance traveled.
Substituting values we have:
Answer:
the work w1 done on the block by the force of magnitude f1 = 60.0 n is:
W1 = 2.40 J
Correct Answer is B.
In a parallel circuit, the voltage is same across all the branches however the current in each branch is different and depends on the resistance of that branch.
Points to Remember:
1) In series circuit current remains the same and voltage varies
2) In parallel circuit voltage remains the same and current varies
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