Answer:
Explanation:
Given
At an elevation of , spacecraft is dropping vertically at a speed of
Final velocity of the spacecraft is
using equation of motion i.e.
Insert the values
Therefore, magnitude of acceleration is .
Answer:
The ratio of kinetic energies of 5 kg object to 20 kg object is 1:1.
Explanation:
Kinetic energy is defined as energy possessed by an object due to its motion.It is calculated by:
Kinetic energy of the 5 kg object.
Mass of object,m = 5 kg
Velocity of an object = v
Kinetic energy of the 20 kg object.
Mass of object,m' = 20 kg
Velocity of an object = v'
The ratio of the kinetic energy of the 5 kilogram object to the kinetic energy of the 20-kilogram object:
Given that, v = 2v'
The ratio of kinetic energies of 5 kg object to 20 kg object is 1:1.
Answer:
B.The force of friction between the block and surface will decrease.
Explanation:
The force of friction is given by
where is the coefficient of friction and is the normal force.
When the student pulls on the block with force at an angle , the normal force on the block becomes
and hence the frictional force becomes
.
Now, as we increase , increases which as a result decreases the normal force , which also means the frictional force decreases; Hence choice B stands true.
<em>P.S: Choice D is tempting but incorrect since the weight </em><em> is independent of the external forces on the block. </em>
All of the above. They all right