Answer:
2.47 m
Explanation:
Let's calculate first the time it takes for the ball to cover the horizontal distance that separates the starting point from the crossbar of d = 52 m.
The horizontal velocity of the ball is constant:
and the time taken to cover the horizontal distance d is
So this is the time the ball takes to reach the horizontal position of the crossbar.
The vertical position of the ball at time t is given by
where
is the initial vertical velocity
g = 9.8 m/s^2 is the acceleration of gravity
And substituting t = 2.56 s, we find the vertical position of the ball when it is above the crossbar:
The height of the crossbar is h = 3.05 m, so the ball passes
above the crossbar.
D. About 25%
25% of stars have compainions
Don't know for sure but I think it would expand and pop
Answer:
Yes, since the choice of the zero o potential energy is arbitrary.
Explanation:
The kinetic energy is due to the motion of the object. The expression for the kinetic energy is as follows;
Here, m is the mass of the object and v is the velocity of the object.
The kinetic energy can not be negative as the velocity is squared. It can be zero and positive.
Potential energy: It is the energy is due to the position of the object.
The expression for the potential energy is as follows;
PE= mgh
Here, g is the acceleration due to gravity and height.
Height can be taken from the reference point, zero which can be taken below zero and above zero. Zero is taken as origin. Below zero, the height is taken as negative and above zero, the height is taken as positive.
The potential energy can be zero, positive and negative.
The total energy is the sum of kinetic energy and potential energy.
E= KE + PE
Here, KE is the kinetic energy and PE is the potential energy.
Therefore, the option (B) is correct.
Your book has applied the chain rule to produce:
dv/dt = dv/dx * dx/dt
Now, we can get dv/dx by:
1) Differentiate
x = vt, with respect to v.
dx/dv = t
Now, if we take the inverse of this, we can obtain dv/dx
dv/dx = 1/t
This is also proven by the fact that dv/dx is the change in velocity and if you multiply it by dv/dx, which is equivalent to dividing by the change in time, as we just proved, then you obtain acceleration.