Answer:
A. 80 N
Explanation:
Since the uniform plank is pivoted at its center at an angle of 30 to the vertical, then it is 90° - 30° = 60° to the horizontal.
Let L be the length of the plank = 4 m, the perpendicular distance of the 4 kg mass form the pivot point is Lcos60°/2. Then the moment of the 4 kg mass about its pivot point is mgLcos60/2 where m = mass = 4 kg and g = acceleration due to gravity = 10 m/s²
Let F be the force applied at 0.5 m from the pivot point. The perpendicular distance of F from the pivot point is 0.5cos60°. Thus the moment of this force about the pivot point is F × 0.5cos60° = 0.5Fcos60°
Since both moments are the same for equilibrium,
mgLcos60/2 = 0.5Fcos60°
F = mgL/(2 × 0.5 m)
F = 4 kg × 10 m/s² × 4 m/1 m
F = 80 kgm/s²
F = 80 N
Answer:
Mercury has the lowest melting point.
Answer:
the net force or resultant force
<h2>The body will move towards the center .</h2>
Explanation:
When the object moves in a circle , the centripetal force is applied towards the center .
Due to inertia of motion , equal and opposite force is developed , acting outwards from center of circle .
This force is called centrifugal force , which balances the centripetal force and the body remains in a circle .
If there is no inertia , this outward force will be zero . thus the body will move towards the center due to its one force called centripetal force .
Given that At full power, the same car can accelerate from 0 to 31 mph in time 1.5 s. How long would it take for the car to accelerate from 0 to 62.0 mph.
Energy= integral (P×dt) = Pt
therefore;
Since kinetic energy = 1/2 mv^2 = Pt
1/2m(31)² = 1.5 P
480.5 m = 1.5 P
P = 320.33 m
Using the other scenario
1/2m(62)² = 320.33mt
= 1922 m =320.33 mt
t = 6.0 sec