W = m · g · h
h = 28.3 m · sin 45° = 28.3 m · 0.707 = 20 m
g = 9.8 m/s²
W = 75 kg · 9.8 m/s² · 20 m
Answer:
W = 14,700 J = 14.7 kJ
Answer:
Explanation:
Given
Ray of light incident on plane making an angle of
with normal
Thus incident angle 
So according to the law of incidence is equal to angle of reflection

thus 
and angle between mirror and reflected ray 

Answer:
d) The 2 athletes reach the same height, because the athletes run with the same speed.
Explanation:
In the whole process , kinetic energy is converted into potential energy .
1/2 m v² = mgh
v² = 2gh
h = v² / 2g
In this expression we see that height attained does not depend upon mass of the object . At the same time it also makes it clear that it depends upon velocity . As the velocity in both the cases are same , height attained by both of them will be same. Hence option d ) is correct.
Answer:
The magnitude of change in momentum is (2mv).
Explanation:
The momentum of an object is given by the product of mass and velocity with which it is moving.
Let the mass of ball is m. A tennis player smashes a ball of mass m horizontally at a vertical wall. The ball rebounds at the same speed v with which it struck the wall.
Initial speed of the ball is v and final speed, when it rebounds, is (-v). The change in momentum is given by :
p = final momentum - initial momentum

So, the magnitude of change in momentum is (2mv).
Answer:
It is a measure of the electric force per unit charge on a test charge.
Explanation:
The magnitude of the electric field is defined as the force per charge on the test charge.
Since we define electric field as the force per charge, it will have the units of force divided by the unit of charge. This implies that the SI unit of electric field is given as Newton/Coulomb (N/C).