Pretty sure the answer is C. Screw: wheel and axle
Answer b protons and electrons
Answer:
The weight of measuring stick is 9.8 N
Explanation:
given information:
the mass of the rock,
= 1 kg
measuring stick, x =1 m
d = 0.25 m
to find the weight of measuring stick, we can use the following equation:
τ = Fd
τ = 0
-
= 0
F_{r} = the force of the rock
F_{s} = the force of measuring stick

= m g
= 1 kg x 9.8 m/s
= 9.8 N
thus, the weight of measuring stick is 9.8 N
Answer: The force needed is 140.22 Newtons.
Explanation:
The key assumption in this problem is that the acceleration is constant along the path of the barrel bringing the pellet from velocity 0 to 155 m/s. This means the velocity is linearly increasing in time.
The force exerted on the pellet is
F = m a
In order to calculate the acceleration, given the displacement d,

we will need to determine the time t it took for the pellet to make the distance through the barrel of 0.6m. That time can be determined using the average velocity of the pellet while traveling through the barrel. Since the velocity is a linear function of time, as mentioned above, the average is easy to calculate as:

This value can be used to determine the time for the pellet through the barrel:

Finally, we can use the above to calculate the force:

Awnser: 600 meters per hour
Step by step explication:
Covert 14 minutes to a fraction of an hour by dividing it by 60, because 60 is how many minutes in an hour and we need to convert it to a decimals. Then divide the distance, 150 meters by the fraction of an hour, .25 to abstain the velocity (speed) of 600 meters per hour.