Explore BrainMass

Explore BrainMass

    Physics: A shop sign weighing 245N is supported by a uniform 155N beam

    Not what you're looking for? Search our solutions OR ask your own Custom question.

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    A shop sign weighing 245N is supported by a uniform 155N beam. Find the tension in the guy wire and the horizontal and vertical forces exerted by the hinge on the beam
    708N, 580N, -6N

    The tires of a car make 85 revolutions as the car reduces its speed uniformly from 90km/h to 60km/h. THE tires have a diameter of .90m a) What was the angular acceleration of each tire? b) if the car continues to decelerate at this rate, how much more time is required for it to stop

    A figure skater can increase her spin rotation rate from an initial rate of 1.0 rev every 2.0s to a final rate of 3.0rev/s. If her initial moment of inertia was 4.6Kgm's^2 what is her final moment of inertia? How does she accomplish this change?

    Two astronauts, one mass 60 and the other 80kg are initially at rest and then they push each other apart. How far apart are they when the lighter astronaut has moved 12 m in outer space?

    A bullet is fired vertically into a 1.40kg block of wood at rest directly. above it. IF the bullet has a mass of 29.0g and a speed of 510m/s how high will the block rise after the bulled becomes embedded in it?

    145g baseball is dropped from a tree 13,0m above the ground. if it hits the ground with a speed of 8.0m/s what is the average force of resistance on it

    A projectile is fired at an angle of 45 degrees from the top of a 165 m cliff with a speed of 175m/s. What will be its speed when it strikes the ground below

    © BrainMass Inc. brainmass.com December 24, 2021, 10:35 pm ad1c9bdddf
    https://brainmass.com/physics/rotation/shop-sign-weighing-supported-uniform-beam-491786

    Attachments

    SOLUTION This solution is FREE courtesy of BrainMass!

    Please see the attached.

    A shop sign weighing 245N is supported by a uniform 155N beam. Find the tension in the guy wire and the horizontal and vertical forces exerted by the hinge on the beam (708N, 580N, -6N)
    The forces acting on the beam are shown.
    Resolving tension T in the guy wire resolved in horizontal and vertical directions gives horizontal component T cos 35o to the left and Tsin 35o upwards.
    Considering equilibrium in horizontal direction we get
    ------------- (1)
    Considering equilibrium in vertical direction we get

    Or ------------- (2)
    Equating moments (torque) of the forces about hinge point we get

    Or
    Or T = 406/sin 35o = 708 N
    Substituting the value of T in equations (1) and (2) we get

    And
    The tires of a car make 85 revolutions as the car reduces its speed uniformly from 90km/h to 60km/h. THE tires have a diameter of .90m
    a) What was the angular acceleration of each tire?
    Like equations of motion for translational motion we can write equations for rotational motion as

    And
    90 km/h = 90*5/18 = 25 m/s and thus
    And 60 km/h = 60*5/18 = 16.67 m/s and thus
    Substituting in third equation we get

    Gives
    b) if the car continues to decelerate at this rate, how much more time is required for it to stop
    Using first equation of motion we get

    Or t = 23 s

    A figure skater can increase her spin rotation rate from an initial rate of 1.0 rev every 2.0s to a final rate of 3.0rev/s. If her initial moment of inertia was 4.6Kgm's^2 what is her final moment of inertia? How does she accomplish this change?

    As there is no external torque acting on her (frictionless floor), her angular momentum remains conserved and thus

    Gives
    This change in moment of inertia is done by bringing her stretched arms and legs closer to her axis of rotation.

    Two astronauts, one mass 60 and the other 80kg are initially at rest and then they push each other apart. How far apart are they when the lighter astronaut has moved 12 m in outer space?

    If we consider the two as a system than there is no external force acting on the system and thus their center of mass does not changes its position. Hence we can write

    Or
    Or
    Or
    Means the other is moving 9 m in opposite direction and thus they are
    12+9 = 21 m apart

    A bullet is fired vertically into a 1.40kg block of wood at rest directly. above it. IF the bullet has a mass of 29.0g and a speed of 510m/s how high will the block rise after the bulled becomes embedded in it?
    As the bullet hits it momentarily, no external force acting on it and hence conserving linear momentum the velocity v of combined mass just after impact is given by
    (M +m) v = m v0
    Or (1.40 + 0.029) v = 0.029*510
    Or v = 10.35 m/s
    The height attain to come to rest at highest point is thus given by
    V2 = u2 + 2as
    Or 0 = (10.35)2 + 2(-9.8)h
    Gives h = 5.47 m

    145g baseball is dropped from a tree 13,0m above the ground. if it hits the ground with a speed of 8.0m/s what is the average force of resistance on it

    The acceleration of the ball is given by (downwards positive)
    v2 = u2 + 2 a s
    Or 8.02 = 0 + 2*a*13.0
    Or a = 2.46 m/s2
    The forces are the weight of the ball and resistance force F
    Thus writing equation of motion according to second law we get
    Mg - F = Ma
    Or F = Mg - Ma = 0.145(9.8 - 2.46) = 1.06 N

    A projectile is fired at an angle of 45 degrees from the top of a 165 m cliff with a speed of 175m/s. What will be its speed when it strikes the ground below

    Resolving its initial velocity of projection
    Horizontal speed of projectile which remains constant throughout the motion
    Vx = 175 cos 45o = 123.7 m/s
    And initial vertical velocity
    Vyo = 175 sin 450 = 123.7 m/s
    As the final vertical position of the projectile is 165 m downwards (upward positive)
    Its speed at the ground is given by
    vy2 = vyo2 + 2*(-9.8)*(-165)
    Or vy2 = 15302 + 3234 = 18536
    Or vy = 136.1 m/s
    And hence the final velocity with which it strike ground is given by

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    © BrainMass Inc. brainmass.com December 24, 2021, 10:35 pm ad1c9bdddf>
    https://brainmass.com/physics/rotation/shop-sign-weighing-supported-uniform-beam-491786

    Attachments

    ADVERTISEMENT