Math/Physics

Question

PLease provide a detailed explanation.

 

1) Suppose that the net external force (push minus friction) exerted on a lawn mower is 51 N parallel to the ground.The mass of the mower is 24kg. What is the acceleration? 

 

2)A physics professor pushes a cart of demonstration equipment to a lecture hall. Her mass is 65kg, the cart is 12kg. And the equipment is 7.0 kg. Calculate the acceleration produced when the professor exerts a backward force of 150 on the floor. All forces opposing the motion, such as friction on the cart's wheel and air resistance total 24.0N.

 

Please Help and add detailed explanatiom

Answer 1

1.  Use Newton's second law:  Force equals mass times acceleration, F = ma.  You know the force (51 N) and you know the mass of the mower (24 kg).  Remembering that a Newton is the same as kg-m/s², solve for acceleration:

 

F = ma

51 kg-m/s² = 24 kg * a

2.125 m/s² =a

 

2. The backward force on the floor is the force of the professor's feet pushing backwards as she walks.  So that force has to accelerate all three items, the cart, the equipment and the professor.  The total mass of those items is 65 + 12 + 7 = 84 kg.

 

The force she is exerting is 150N and it is opposed by a force of 24N, for a net force of 126N

 

So again use F = ma

 

126 = (65 + 12 + 7) a

126 = 84 a

126 / 84 = a

1.5 m/s² = a