Answer:
the final temperature = 74.33°C
Explanation:
Using the expression Q = mcΔT for the heat transfer and the change in temperature .
Here ;
Q = heat transfer
m = mass of substance
c = specific heat
ΔT = the change in temperature
The heat Q required to change the phase of a sample mass m is:
Q = m
where;
is the latent heat of vaporization.
From the question ;
Let M represent the mass of the coffee that remains after evaporation is:
ΔT = 
where;
m = 2.50 g
M = (240 - 2.50) g = 237.5 g
= 539 kcal/kg
c = 1.00kcal/kg. °C
ΔT = 
ΔT = 5.67°C
The final temperature of the coffee is:
ΔT
where ;
= initial temperature = 80 °C
= (80 - 5.67)°C
= 74.33°C
Thus; the final temperature = 74.33°C
Answer:
Option c is correct
Explanation:
There are two types of collisions-elastic collision and inelastic collision.
In elastic collision, both kinetic energy and total momentum are conserved. On the other hand, in inelastic collision, total momentum is conserved but kinetic energy is not conserved. Thus, option b and d are incorrect.
Total energy is always conserved in both types. Thus, option a is incorrect.
In a perfectly inelastic collision, objects stick together. This happens because maximum kinetic energy is dissipated and used in bonding of the two objects. Thus, correct option is c.
Answer:
Average velocity of an object is equal to the instantaneous velocity when it's acceleration is zero.
Explanation:
Answer: c. they will hit the ground at the same time
Explanation:
The volume of both objects is almost the same, so the force of friction will be the same in each one, so we can discard it.
Now, when yo drop an object, the acceleration of the object is always g = 9.8m/s^2 downwards, independent of the mass of the object.
So if you drop two objects with the same volume but different mass, because the acceleration is the same for both of them, they will hit the ground at the same time, this means that the density of the object has no impact in how much time the object needs to reach the floor.
So the correct option is c
Answer:
B. +5.75 m/s
Explanation:
When there are two bodies, a and b, whose velocities measured by a third observer (in this case, the ground) are 
and 
respectively, the relative velocity of B with respect to A is given by:
Thus, the velocity of the girl relative to the lawnmower is:
