The correct answer is (B)
Which is (kQ1Q2) / d^2
Let the cannonball be thrown at a height of h above ground.
Then the potential energy of the ball is
V = m*g*h
where
m = the mass of the ball
g = 9.8 m/s²
Also, the kinetic energy of the ball is
K = (1/2)mu²
where
u = 5 m/s, the vertical launch velocity.
Ignore wind resistance.
Because the total energy is preserved, the total energy (n the form of only kinetic energy) when the ball strikes the ground is
(1/2)mV²
where V = vertical velocity when the ball strikes the ground.
Expressions for both the initial and final energy are equal regardless of whether the ball s thrown downward or upward.
Therefore there is no difference in the landing speed.
Answer: There is no difference.
Answer:

Explanation:
An object is at rest along a slope if the net force acting on it is zero. The equation of the forces along the direction parallel to the slope is:
(1)
where
is the component of the weight parallel to the slope, with m being the mass of the object, g the acceleration of gravity,
the angle of the slope
is the frictional force, with
being the coefficient of friction and R the normal reaction of the incline
The equation of the forces along the direction perpendicular to the slope is

where
R is the normal reaction
is the component of the weight perpendicular to the slope
Solving for R,

And substituting into (1)

Re-arranging the equation,

This the condition at which the equilibrium holds: when the tangent of the angle becomes larger than the value of
, the force of friction is no longer able to balance the component of the weight parallel to the slope, and so the object starts sliding down.
I think the best way to answer to this kind of question because some of the elements are missing specially the mass of the book is just states the variables and assigned as the mass of an object. So the initial velocity of an object starts at zero and increase rapidly by 9.8 m/s^2 because it is due to gravity
Answer:4m/s
Explanation:The car is moving with constant acceleration therefore average speed is equal to distance over time to find the distance covered we multiple the speed by the time which gives 20 metres meaning after every 20 metres it uses a speed of 2m/s so for 40 metres it's going to be 40 x2 over 20 giving us 4m/s