Newton's law problem??

Question

the 30lb blockB is supported by the 55lb blockA and is attached to a chord to w/c a 50lb horizontal force is applied as shown. neglecting friction, determine:

acceleration of BlockA?

acceleration of Block B relative to A?

Answer 1

Hi, Ray,

Please share the figure with us.

Thx.

-Fred

Answer 2

Hi,

As there is no picture, I am assuming that the chord passes over a pulley.

The difference in the weights = 55 - 30 = 25 lb

therefore effective mass is 25 lb as the rest cancels each other.

m = 25

F = 50 lb

also F = ma

=> a = F/m = 50/25 = 2 ft/sec^2

This is the speed of block w.r.t. ground. and this is towards the direction of force.

Similarly Block B will also travel with an acceleration of 2 ft/sec^2 but against the direction of force. So the acceleration of block B relative to block A is 2+2 = 4 ft/sec^2

Your answers:

acceleration of BlockA = 2 ft/sec^2

acceleration of Block B relative to A = 4 ft/sec^2

Hope to answer you well. Keep smiling. bye.