14.7k views
2 votes
Hello,
please the answers should be for A-LEVEL students.
thank you very much

Hello, please the answers should be for A-LEVEL students. thank you very much-example-1
User Matty
by
5.3k points

1 Answer

5 votes

Answer:

see attached for a diagram and loads

Step-by-step explanation:

The mass of the man represents a downward force of ...

F = ma

F = (85 kg)(9.8 m/s²) = 833 N

at a point 1.5 meters from one support. In the attached diagram, the man is standing left of center, so is 1.5 m from the left support, and 4.9 m from the right support.

The mass of the beam represents a downward force of ...

F = (15 kg)(9.8 m/s²) = 147 N

This is effectively modeled by a force acting on the center of the beam, 3.2 m from each support. The distance between supports is 6.8 -2(0.2) = 6.4 m.

The net torque on the beam is zero. This means we can sum the torques at either support and set them to zero. If we let s1 represent the upward force supplied by the left pillar, and s2 the upward force supplied by the right pillar, the two torque equations are ...

torque = force × distance

CW torque about the left pillar: 833×1.5 +147×3.2 -s2×6.4 = 0

s2 = 1719.9/6.4 ≈ 268.7 . . . newtons

CCW torque about the right pillar: -s1×6.4 +833×4.9 +147×3.2 = 0

s1 = 4552.1/6.4 ≈ 711.3 . . . newtons

The magnitudes of the loads carried by the supports are 268.7 N and 711.3 N.

__

Check

For static equilibrium, the sum of upward forces must match the sum of downward forces:

268.7 +711.3 = 980 . . . . newtons (total of upward forces)

883 +147 = 980 . . . . . . . newtons (total of downward forces)

Hello, please the answers should be for A-LEVEL students. thank you very much-example-1
User Richard Grimshaw
by
5.5k points