Answer: 4
The mechanical advantage is the ratio of the force exerted by the object to the force applied to do work on it.
Here, Jeff tried to lift a rock weighing 600 pounds by wedging board under the rock. Jeff who weighs 150 pounds uses all his weight to exert force on lever and lift rock.
Mechanical advantage, 
Therefore, the mechanical advantage that lever provided to Jeff in lifting rock is 4.
Answer:
Speed of the alpha particle is
Explanation:
We have given charge on alpha particle 
Mass of the alpha particle 
Potential difference 
We have to find the speed of the alpha particle
From energy conservation we know that



Answer: Non metal.
Explanation: Carbon has 4 electrons in it’s valence shell which makes it a metalloid but commonly it is considered as a non metal.
Answer:
A.
Explanation:
We are given that

Density,
Tension,T=38 N
We have to find the density of liquid.


Volume,V=




Option A is true.