A 20.0-kg box rests on a table. (a) What is the weight of the box and the normal force acting on it? (b) A 10.0-kg box is placed on top of the 20.0-kg box. Determine the normal force that the table exerts on the 20.0-kg box and the normal force that the 20.0-kg box exerts on the 10.0-kg box.

A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only $0.75$ of her regular weight. Estimate the acceleration of the elevator, and find the direction of acceleration.

A $14.0-\mathrm{kg}$ bucket is lowered vertically by a rope in which there is $163 \mathrm{~N}$ of tension at a given instant. What is the acceleration of the bucket? Is it up or down?

How much tension must a cable withstand if it is used to accelerate a $1200 \mathrm{~kg}$ car vertically upward at $0.70 \mathrm{~m} / \mathrm{s}^2$ ?

What weight of water is displaced by a floating ship whose mass is $m_s=10^5~\text{kg}$? What is the buoyant force that acts on this ship?

How much tension must a cable withstand if it is used to accelerate a $1200-\mathrm{kg}$ car vertically upward at $0.70 \mathrm{~m} / \mathrm{s}^2$ ?

(a) What is the buoyant force on 0.90 kg of ice floating freely in liquid water? (b) What is the buoyant force on 0.90 kg of ice held completely submerged under water?

An object weighing 45 newtons in air is suspended from a spring scale. The spring scale reads 22 newtons when the object is fully submerged in water. Calculate the buoyant force on the object.

Calculate the buoyant force due to the surrounding air on a man weighing 800 N. Assume his average density is the same as that of water.

If an object weighing 50 N displaces a volume of water with a weight of 10 N, what is the buoyant force on the object? a. 60 N b. 50 N c. 40 N d. 10 N

A pump is being used to transfer water from an open tank to one that has air at $500 \mathrm{kPa}$ above the water,if the left-hand tank is also sealed and air pressure above the water is $68 \mathrm{kPa}$, calculate the pump power.. Suppose that the level of the surface in each tank is the same.

What is the weight of a 76-kg astronaut on Earth.

A water storage tank with a roof that is in the shape of a cone has a diameter of 10 ft. The height of the cylindrical part of the tank is 15 ft. The slant height of the roof is 8 ft. What is the surface area of the entire tank?

A rooftop water storage tower, is filled with fresh water to a depth of 6.4 m. (a) What is the pressure 4.5 m below the surface of the water? (b) Why are the circular metal bands more closely spaced near the base of the tank?