OAR OAR Mechanical Comprehension: Forces 5

Question 1

A hydraulic press has an input piston of area 0.01 m² and an output piston of area 0.1 m². If an input force of 50 N is applied, what is the output force?

Accepted Answer

500 N

Answer

Pressure is equal throughout: F₂ = F₁ × (A₂/A₁) = 50 × (0.1/0.01) = 500 N.

Question 2

Which statement correctly describes the relationship between mass and weight?

Accepted Answer

Weight is the force of gravity on an object; mass is the amount of matter

Answer

Weight = mg is a gravitational force measured in Newtons, while mass is an intrinsic property measured in kilograms.

Question 3

An object is pulled by a 100 N force at 37° above the horizontal on a rough floor (μk = 0.3). The object weighs 200 N. What is the normal force from the floor?

Accepted Answer

139.8 N

Answer

Normal force = Weight − F sin 37° = 200 − 100(0.602) ≈ 200 − 60.2 = 139.8 N.

Question 4

A 20 kg box accelerates at 3 m/s² on a surface with kinetic friction. If the applied horizontal force is 100 N, what is the friction force?

Accepted Answer

40 N

Answer

Net force = ma = 20 × 3 = 60 N; friction = Applied − Net = 100 − 60 = 40 N.

Question 5

A hanging sign is supported by two cables: one horizontal and one at 60° above horizontal. If the sign weighs 120 N, what is the tension in the angled cable?

Accepted Answer

138.6 N

Answer

Vertical equilibrium: T sin 60° = 120 N → T = 120/0.866 ≈ 138.6 N.

OAR Test Practice Test

OAR Test Practice Test

OAR OAR Mechanical Comprehension: Forces 5