Figure shows a claw hammer as it is being used to pull a nail out of a horizontal board. If a force of $150 \mathrm{~N}$ is exerted horizontally as shown, find (a) the force exerted by the hammer claws on the nail and (b) the force exerted by the surface on the point of contact with the hammer head. Assume that the force the hammer exerts on the nail is parallel to the nail.

How are the electric fields produced by individual charges combined to obtain the total electric field?

The hand clamp is constructed using a squarethreaded screw having a mean diameter of $36 {mm}$, a lead of $4 {mm}$, and a coefficient of static friction at the screw of $\mu_s=0.3$. To tighten the screw, a force of $F=20 {N}$ is applied perpendicular to the handle. Determine the clamping force in the board $A B$.

A block placed under the head of the claw hammer as shown greatly facilitates the extraction of the nail. If a 200-N pull on the handle is required to pull the nail, calculate the tension T in the nail and the magnitude A of the force exerted by the hammer head on the block. The contacting surfaces at A are sufficiently rough to prevent slipping. (see the given figure)

Lifting a weight to a height of 20 m takes 20 s for one crane and 10 s for another. Is there any difference in the amount of work done on the weight by each crane?

Explain how (a) an electric current is produced when only a part of a single wire loop moves through a magnetic field and how (b) an electric current is produced when an external magnetic flux changes through a closed loop of wire.

We know that a claw hammer is used to pull a nail out of a horizontal board. A force of $150 \mathrm{~N}$ is exerted horizontally as shown. Determine the force exerted by the surface on the point of contact with the hammerhead. Assume that the force the hammer exerts on the nail is parallel to the nail.

In the interaction between a hammer and the nail it hits, is a force exerted on the nail? On the hammer? How many forces occur in this interaction?

Determine the force T required to hold the uniform bar of mass m and length L in an arbitrary angular position $\theta$. Plot your result over the range $0 \leq \theta \leq 90^{\circ}$, and state the value of T for $\theta=40^{\circ}$.

The uniform 14-ft pole weighs 150 lb and is supported as shown. Calculate the force P required to move the pole if the coefficient of static friction for each contact location is 0.40.

A uniform beam resting on two pivots has a length $L=$ GP $6.00 \mathrm{~m}$ and mass $M=90.0 \mathrm{~kg}$. The pivot under the left end exerts a normal force $n_1$ on the beam, and the second pivot located a distance $\ell=4.00 \mathrm{~m}$ from the left end exerts a normal force $n_2$. A woman of mass $m=$ $55.0 \mathrm{~kg}$ steps onto the left end of the beam and begins walking to the right. The goal is to find the woman's position when the beam begins to tip.
(g) Check the answer to part (e) by computing torques around the first pivot point.

A uniform beam resting on two pivots has a length $L=$ GP $6.00 \mathrm{~m}$ and mass $M=90.0 \mathrm{~kg}$. The pivot under the left end exerts a normal force $n_1$ on the beam, and the second pivot located a distance $\ell=4.00 \mathrm{~m}$ from the left end exerts a normal force $n_2$. A woman of mass $m=$ $55.0 \mathrm{~kg}$ steps onto the left end of the beam and begins walking to the right. The goal is to find the woman's position when the beam begins to tip.
(c) Where is the woman when the normal force $n_1$ is the greatest?

A uniform beam resting on two pivots has a length $L=$ GP $6.00 \mathrm{~m}$ and mass $M=90.0 \mathrm{~kg}$. The pivot under the left end exerts a normal force $n_1$ on the beam, and the second pivot located a distance $\ell=4.00 \mathrm{~m}$ from the left end exerts a normal force $n_2$. A woman of mass $m=$ $55.0 \mathrm{~kg}$ steps onto the left end of the beam and begins walking to the right. The goal is to find the woman's position when the beam begins to tip.
(d) What is $n_1$ when the beam is about to tip?

A uniform beam resting on two pivots has a length $L=$ $6.00 \mathrm{~m}$ and mass $M=90.0 \mathrm{~kg}$. The pivot under the left end exerts a normal force $n_1$ on the beam, and the second pivot located a distance $\ell=4.00 \mathrm{~m}$ from the left end exerts a normal force $n_2$. A woman of mass $m=$ $55.0 \mathrm{~kg}$ steps onto the left end of the beam and begins walking to the right as we discussed earlier. The goal is to find the woman's position when the beam begins to tip.
(a) What is the appropriate analysis model for the beam before it begins to tip?