Answer with Explanation:
We are given that
Force acts on a pebble=
N
Position vector=
m
a.We have to find the resulting torque on the pebble about origin.
Torque=
Substitute the values then we get

Torque=
N-m
By using 
b.

Torque about point (2,0,-3)

N-m
Answer:
i dont know the answer for this question sorry for the misunderstanding
Explanation:
Answer:
Q = 2.95*10^5 kJ
Explanation:
In order to calculate the energy required to melt the cooper, you first calculate the energy required to reach the boiling temperature. You use the following formula:
(1)
m: mass of cooper = 540 kg
c: specific heat of cooper = 390 J/kg°C
Tb: boiling temperature of cooper = 1080°C
T1: initial temperature of cooper = 20°C
You replace the values of the parameters in the equation (1):

Next, you calculate the energy required to melt the cooper by using the following formula:
(2)
Lf: melting constant of cooper = 134000J/kg

Finally, the total amount of energy required to melt the cooper from a temperature of 20°C is the sum of Q1 and Q2:

The total energy required is 2.95*10^5 kJ
ANSWER is c
HOPR THIS WILL BE HELPFUL
Wave reflection occurs when waves reflect or rebound off of a surface. This is like an echo because the sound waves are reflected from a distant surface