Answer:
Equal number of protons and electrons
Explanation:
This principle of proton and electron equality was used by J.J. Thompson in the discovery of proton. After he had discovered the electron. He discovered that since atoms are electrically neutral, that means there must be equal number of protons to balance out the electrons present in the atom.
Answer:
577g
Explanation:
Given parameters:
Temperature change = 5.9°C
Amount of heat lost = 427J
Unknown:
Mass of the block = ?
Solution:
The heat capacity of a body is the amount of heat required to change the temperature of that body by 1°C.
H = m c Ф
H is the heat capacity
m is the mass of the block
c is the specific heat capacity
Ф is the temperature change
Specific heat capacity of lead is 0.126J/g°C
m = H / m Ф
m =
= 577g
Mass of the lead block is 577g
Answer:

Explanation:
given,
street light height = 13 ft
man height = 6.3 ft
speed of the man = 3.5 ft/sec



hL = H(L-x)
hL = HL-Hx


L = 1.94 x



The dog’s speed is
A) 0.61 m/s
Answer:
7.5 kg
Explanation:
We are given that

Length of plank, l=3 m
Distance of fulcrum from one end of the plank=1 m

We have to find the mass must be on the other end if the plank remains balanced.
Let m be the mass must be on the other end if the plank remains balanced.
In balance condition






Hence, mass 7.5 kg must be on the other end if the plank remains balanced.