1. Force questions that require Calculations !!!!!!!!!!!
What fun!

2. A boy pulls horizontally with a force of 100N on a box of
Mass 50kg. Find the resulting acceleration if (a) Force of friction = 0; (b) Force of friction = 25N. + FN -
Ffr
Fappl + Fg -

3. A boy pulls horizontally with a force of 100N on a box of
Mass 50kg. Find the acceleration motion if (a) Force of friction = 0;
(b) Force of friction = 25N. + FN
(a)
Fx = Fappl – Ffr = ma
100N = (50kg)a
a = 2 m/s2
Fy = FN – Fg = ma = 0
(there is no motion or
acceleration in the
y-direction) -
Ffr
Fappl + Fg -

4. A boy pulls horizontally with a force of 100N on a box of
Mass 50kg. Find the acceleration motion if (a) Force of friction = 0;
(b) Force of friction = 25N. + FN
(b)
Fx = Fappl – Ffr = ma
100N – 25N = (50kg)a
a = 1.5 m/s2
NOTE:
Fy = FN – Fg = ma = 0
FN = (50kg)(9.8)=490N
(there is no motion or
acceleration in the
y-direction) -
Ffr
Fappl + Fg -

5. A boy pulls at a 30˚ angle with a force of 100N on a box of
Mass 50kg. Find the resulting acceleration if force of friction = 0. + FN -
Fappl
Ffr + Fg -

6. A boy pulls at a 30˚ angle with a force of 100N on a box of
Mass 50kg. Find the resulting acceleration if force of friction = 0. + FN
Fx = Fappl cos30 – Ffr = ma
100N cos30 = (50kg)a
a = 1.73 m/s2
NOTE:
Fy = FN + Fappl sin30 – Fg = ma
FN sin30 – (50)(9.8) = 0
(there is no motion or acceleration in the y-direction)
FN = = 440N -
Fappl
Ffr + Fg -

7. A boat is pulled with two forces as shown (one at a 45˚ angle and one at a 37 ˚ angle. Calculate the net force on the boat. +
F1 = 40N
45˚ +
37˚
F2 = 30N

8. A boat is pulled with two forces as shown (one at a 45˚ angle and one at a 37 ˚ angle. Calculate the net force on the boat. +
F1x = F1cos45 = 28.3 N
F1y = F1sin45 = 28.3N
F2x = F2cos37 = 24.0N
F2y = F2sin37 = -18.1N
Fx = F1x + F2x = 52.3N
Fy = F1y + F2y = 10.2N
F = (Fx2 + Fy2)1/2 = 53.3N
tanΘ = 10.2/52.3
Angle is 11.0˚
F1 = 40N
45˚ +
37˚
F2 = 30N

9. When a flexible cord pulls on an object (assume the cord has
Negligible mass), calculate the acceleration of the system. The
Pulling force is 40N and the boxes have a mass of 10kg each. + + FN FN FT FT
Fappl + Fg Fg - -

10. When a flexible cord pulls on an object (assume the cord has
Negligible mass), calculate the acceleration of the system. The
Pulling force is 40N and the boxes have a mass of 10kg each. + + FN FN FT FT m2 m1
Fappl +
NOTE:
a is the same for both
boxes.
a= 2 m/s2 Fg Fg - -
Fx=FT=m2a
Fx=Fappl - FT=m1a
Fappl – m2a = m1a

11. You are given an Atwood’s Machine. There are two masses
hanging from a massless pulley. M1 is 15kg and M2 is 28kg.
Calculate acceleration of the masses and the force of tension
in the rope. FT FT m2 m1
Fg2
Fg1 - +

12. You are given an Atwood’s Machine. There are two masses
hanging from a massless pulley. M1 is 15kg and M2 is 28kg.
Calculate acceleration of the masses and the force of tension
in the rope. - + FT FT
Fg1 – Fg2 = (m1 + m2)a
(15kg)(9.8) – (28)(9.8) = (43kg)(a) m2 m1
NOTE:
a is the same for both
masses.
a= m/s2
a is to the left mass.
Fg2
Fg1 - +
FT – Fg2 = m2a
-FT + Fg1 = m1a