Laws of Motion

Q1.A spring scale reads 50 N when an object is suspended at rest. If the system is in free fall, the reading is:

• A50 N
• B25 N
• C100 N
• D0 N

Q2.The coefficient of static friction is generally:

• Aless than kinetic friction
• Bgreater than kinetic friction
• Cequal to kinetic friction
• Dindependent of surface condition

Q3.In the Atwood machine (two masses m1 and m2 over a frictionless pulley, m1 > m2), the tension in the string is:

• A(m1 - m2)g
• B(m1 + m2)g/(m1 - m2)
• C2m1 m2 g/(m1 + m2)
• Dm1 m2 g/(m1 - m2)

Q4.A 10 kg block is pushed against a vertical wall by a horizontal force of 50 N. If mu_s = 0.3, what minimum additional horizontal force prevents the block from sliding? (g = 10 m/s^2)

• ANo additional force needed — block doesn't slide
• B15 N vertical force
• C50 N additional horizontal force
• D100 N total horizontal force

Q5.A man of mass 80 kg stands in a lift going down with acceleration 2 m/s^2. His apparent weight is (g = 10 m/s^2):

• A640 N
• B800 N
• C960 N
• D1000 N