Answer = 31.5J (rounded to 1dp)
The question wants to find the work done, where work done can be calculated in the equation:
Work done = Force x Distance
The force is not given in the question, however they give the acceleration and mass, so you can calculate the force using Newton's second law:
Force = Mass x Acceleration
First, calculate the force. The mass is 45kg for the 3 boxes and the acceleration is 12.3m/s^2.
Force = 45 x 12.3
Force = 553.5N
Now that you have the force (553.5N) and distance (57cm), substitute those values into the equation for work done.
Make sure to convert the 57cm into metres (into SI units), otherwise the answer would be wrong.
57cm = 0.057m
Work done = Force x Distance
Work done = 553.5 x 0.057
Work done = 31.5J (rounded to 1dp)
The kinetic energy of the bullet is 20.4 kJ.
<u>Explanation:</u>
Kinetic energy of a bullet will be equal to the product of mass of the bullet with the square of velocity or speed of the bullet and then the half of that product value.
But here the mass of the bullet is not given, instead the weight of the bullet is given in terms of force. So from this, we have to first find the mass of the bullet.
We know that as per Newton's second law of motion, force is directly proportional to the product of mass and acceleration. So here the acceleration will be equal to the acceleration due to gravity as it is weight of the object.
So F = mg
0.10 N = m × 9.8
So ,the mass of the bullet is 0.0102 kg.
Now, we know the mass and velocity of the bullet is given as 2000 m/s.
So,
kinetic energy = 
× m × v²
kinetic energy = 0.5 × 0.0102 × 2000 × 2000 = 20.4 kJ
Thus, the kinetic energy of the bullet is 20.4 kJ.
Answer:
oop i cant see the anwer choices correctly
Explanation:
Atomic number, atomic mass
First, we must find the power consumed by the light bulb. This is given by:
Power = voltage * current
Power = 250 * 0.8
Power = 200 W = 0.2 kW
Now, we must calculate the number of hours that the bulb is used, as the price given to us is in Rs/kWh. This is:
8 hours per day * 30 days
= 240 hours
Total kWh = 0.2 * 240
Total kWh = 48 kWh
Bill = 3 * 48
Bill = 144 Rs
