Answer:
8.61 min
Explanation:
original mass= 12.65
first half life = 12.65/2 = 6.325
second half life = 6.325/2 = 3.1625
Note : 3.1625 is the closest to the value (3.115) given so we work with it
total time for decay =17.22
therefore two decays = 17.22/2= 8.61
If ball remains in air for total time T = 0.85 s
this is also known as time of flight
In order to find the time of flight we can use kinematics

so for complete motion its displacement in y direction will be zero



now we know that net velocity of the ball is 8 m/s
while is y direction component we got is vy = 4.165 m/s
now by component method we can say




so it is projected at an angle of 31.4 degree above horizontal
If you exert a force on an object in motion, then depending on the
direction of the force you exert and the direction in which it's already
moving, you may speed it up, slow it down, or change the direction
of its motion. Any of these changes is called an acceleration.
In addition to that, you'll change the object's momentum and kinetic energy.
They may increase or decrease ... again depending on the directions of the
motion and the new force.
You will not change the object's mass, inertia, weight, color, cost,
political affiliation, or gender preference.
Answer:
4.6 
Explanation:
Since the table is frictionless, there is no force of dynamic friction between table an block when the horizontal force is applied to it on Earth. Exactly the same is true when the table is taken to the Moon. Therefore, the Net Force acting on the object in both cases when the object accelerates, is the external horizontal force.
Notice that on Earth and on the Moon, the weight of the object (vertical and pointing up) is compensated by the normal force of the table on the object (pointing up and of the same magnitude as the weight) that precludes movement in the vertical direction. So in both cases, its acceleration will only be due to the horizontal force.
We use the equation for Net Force to find the mass of the object:

We use this mass (since the mass of the object is a constant independent of where the object is) to find the acceleration the object will experience when the 20 N horizontal force is applied on it on the Moon:
