Mechanics | Relativity Answers

A box of books weighing 316 N moves with
a constant velocity across the floor when it is
pushed with a force of 376 N exerted downward at an angle of 31.2◦ below the horizontal.
Find µk between the box and the floor.

Now the student moves the box up a ramp
(with the same coefficient of friction) inclined
at 10.6
◦ with the horizontal.
b) If the box starts from rest at the bottom
of the ramp and is pulled at an angle of 27.6
◦
with respect to the incline and with the same
183 N force, what is the acceleration up the
ramp?
Answer in units of m/s
2
.

A student moves a box of books down the hall
by pulling on a rope attached to the box. The
student pulls with a force of 187 N at an angle
of 20.4
◦
above the horizontal. The box has a
mass of 27.3 kg, and µk between the box and
the floor is 0.22.
The acceleration of gravity is 9.81 m/s
2
.
Find the acceleration of the box.
Answer in units of m/s
2

A 1.8 kg otter starts from rest at the top of a
muddy incline 83.5 cm long and slides down
to the bottom in 0.50 s.
What net external force acts on the otter
along the incline?
Answer in units of N.

A 27 kg chair initially at rest on a horizontal
floor requires a 176 N horizontal force to set
it in motion. Once the chair is in motion, a
148 N horizontal force keeps it moving at a
constant velocity.
The acceleration of gravity is 9.81 m/s
2
.
a) What is the coefficient of static friction
between the chair and the floor?

A 77.0 kg box slides down a 25.0◦
ramp with
an acceleration of 3.30 m/s2
.Find µk between the box and the ramp.
The acceleration of gravity is 9.81 m/s
2
.

A 20 kg chair initially at rest on a horizontal
floor requires a 161 N horizontal force to set
it in motion. Once the chair is in motion, a
133 N horizontal force keeps it moving at a
constant velocity.
The acceleration of gravity is 9.81 m/s
2
.
a) What is the coefficient of static friction
between the chair and the floor?

Now the student moves the box up a ramp
(with the same coefficient of friction) inclined
at 10.1
◦ with the horizontal.
b) If the box starts from rest at the bottom
of the ramp and is pulled at an angle of 26.7
◦
with respect to the incline and with the same
173 N force, what is the acceleration up the
ramp?
Answer in units of m/s
2
.

A student moves a box of books down the hall
by pulling on a rope attached to the box. The
student pulls with a force of 173 N at an angle
of 26.7
◦
above the horizontal. The box has a
mass of 42.4 kg, and µk between the box and
the floor is 0.2.
The acceleration of gravity is 9.81 m/s
2
.
Find the acceleration of the box.
Answer in units of m/s
2
.

A 2.5 kg otter starts from rest at the top of a
muddy incline 86.2 cm long and slides down
to the bottom in 0.50 s.
What net external force acts on the otter
along the incline?
Answer in units of N.