A pure substance is a substance that is made with only one type of molecule
Answer:

Explanation:
Given data
Coefficient of performance of a residential heat pump=1.6
Electrical power P=4kW
Required
Heat Q
Solution
The rate of heat produced is given as

Substitute the given values
So
There's not enough information in the question to calculate the answer.
Knowing the child's walking speed, we would need to know how often s/he takes a step in order to calculate the length of their legs.
U=70 , v= 0, t=35, a=?
v=u+at
0=70+a(35)
-70=35a
a=-2m/s^2
Decelerate 2ms^-2 or acceleration is -2ms^-2