use the hints only if you are confused.
Main idea: torque = distance x force
The units for force is N, the units for distance is m so the units for torque is N.m
LAB TORQUE
1)
You use 2 wrenches to rotate a nut.
The large wrench is 24 cm long and the small one is 12 cm long. You apply a 50N force at the end to rotate the nut.
Compute the torques applied to each of the wrench. Which one will be easier to rotate ?
2)
You try to lift a big rock. the small rock is your fulcrum or axis of rotation.
l is the lever of arm. It is the perpendicular distance from the fulcrum to the
line of action of the force.
A) If you push at the end of the stick with a force of 100 N, what is the torque? l = 2m
B) if you push twice as close to the fulcrum, what is the torque ? What does it mean?
C) this system is called a ____________ , this machine magnify your force.
D) if you multiply the lever arm by 2 (l is multiplied by 2), the torque is multiplied by __________
so it is easier to lift the rock
3)
If you to reach equilibrium the torque on the right of the fulcrum has to balance the torque on the left.
(the net torque is then zero)
A) Find the torque applied by the 5N weight. Tr = _________ (convert the 20 cm into m)
B) solve for the distance l between the 3N weight and the fulcrum so equilibrium is reached.
(hint : Torque on the left = torque on the right)
4)
If F1 = 10N and l1 = 30 cm
Find F2 if l2 = 25 cm
hints: F1 x l1 = F2 x l2 solve for F2
5)
A) If F2 = 10 N and l2 = 20 cm
Find F1 if l1 is twice l2.
hints: F2 x l2 = F1 x l1 substitute l1 by 2 x l2 , solve for F1
SO IF YOU MULTIPLY YOUR DISTANCE BY 2, THE TORQUE IS MULTIPLY BY 2
based on that observation answer this question
B) if you want to play seesaw with your sister, 3 times lighter than you,
where would you sit relative to the fulcrum? Your sister is sitting at 3m from the fulcrum ?
hints: take an example. you = 90 kg (F1). sister = 30 kg (F2) and l2 = 3m solve for l1
6) A motorcycle head bolt is torqued to 25.0 Nm . What length shaft do we need on a wrench
to exert a maximum force of 70.0 N?
hint: torque = force x distance, solve for distance.
7) An automobile bolt is torqued to 27.0 Nm. If the length of the wrench is 30.0 cm what force
is applied to the wrench ? (convert cm to me before computing the force)
8) if 13 Nm of torque is applied to a bold with an applied force of 28 N, what is the length of the wrench ?
9) 2 persons sit on a seesaw. Jack sits 2.05 m from the fulcrum and has a mass of 60kg.
Gill sits at 3.0 from the fulcrum. The system is in equilibrium. WHat is the mass of Gill ?
hints: torque 1 = torque 2 so W1 x L1 = W2 x L2 or m1 x L1 = m2 x L2, solve for m2
10) optional only . For Physics lovers
A uniform meter rule of mass 100g balances at the 40cm mark when a mass X is placed
at the 10cm mark. What is the value of X?
hints: the fulcrum is at the 40cm marks, the weight of the ruler is at the 50cm mark
and weight of X is at the 10cm mark. draw a diagram.
