Answer:
the friction force on this box is closest to 45.9 N.
Explanation:
given data
Weight of the box W = 150 N
accelerating uniformly = 3.00 m/s²
coefficient of kinetic friction = 0.400
coefficient of static friction = 0.600
solution
we know box does not move relative to the wagon
we get here friction force that is express as
friction force = mass × acceleration ..............1
here mass = weight ÷ g
mass =
= 15.3 kg
put value in equation 1 we get
friction force = 15.3 kg × 3
friction force = 45.9 N
So, the friction force on this box is closest to 45.9 N.
Answer : The correct option is, (d) 
Explanation :
In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.


where,
= specific heat of copper = 
= specific heat of water = 
= mass of copper = 120 g
= mass of water = 300 g
= final temperature of mixture = 
= initial temperature of copper = ?
= initial temperature of water =
Now put all the given values in the above formula, we get:


Therefore, the temperature of the kiln was, 
Answer:
V=20cm/s
Explanation:
The average speed is the distance total divided the time total:

First stage:
T1=5s

But,
(decelerates to rest)
then: 
on the other hand:

X1=75cm
Second stage:
T2=5s

X2=125cm
Finally:
X=X1+X2=200cm
T=T1+T2=10s
V=X/T=20cm/s
Answer:0.502kg
Explanation:
F4om the relation
Power x time = mass x latent heat of vapourization
P.t=ML
1260 * 15 *60 = M * 22.6 * 10^5
M= 1134000/(22.6 *10^5)
M=0.502kg=502g