Q: A $$10\ \mathrm{kg}$$ object is suspended from a wire. If the wire stretches $$0.005\ \mathrm{m}$$ under the load and has a length $$2\ \mathrm{m}$$ and cross-sectional area $$0.0005\ \mathrm{m}^2$$, what is the Young's modulus of the wire?

$$7.84 \times 10^7$\ \mathrm{N/m^2$}$$

Question 1

A solid disk of mass $$2\ \mathrm{kg}$$ and radius $$0.5\ \mathrm{m} is $$rotating at $$10\ \mathrm{rad/s}. $$What is its rotational kinetic energy?

Accepted Answer

$$25\ \mathrm{J}$$

Question 2

A uniform beam of length $$4\ \mathrm{m}$$ and mass $$20\ \mathrm{kg} is $$supported at its ends. A $$60\ \mathrm{kg}$$ person stands $$1\ \mathrm{m}$$ from the left end. What is the force exerted by the right support?

Accepted Answer

$$245\ \mathrm{N}$$

Question 3

A $$0.2\ \mathrm{kg}$$ ball moving at $$5\ \mathrm{m/s}$$ collides elastically with a stationary $$0.3\ \mathrm{kg}$$ ball. What is the velocity of the $$0.2\ \mathrm{kg}$$ ball after the collision?

Accepted Answer

$$1\ \mathrm{m/s}$$

Question 4

A $$5\ \mathrm{kg}$$ object is lifted vertically $$3\ \mathrm{m} at $$constant speed. What is the work done by gravity?

Accepted Answer

$$-147\ \mathrm{J}$$

Question 5

A spring with spring constant $$k = 200\ \mathrm{N/m} is $$compressed $$0.1\ \mathrm{m}. $$What is the elastic potential energy stored?

Accepted Answer

$$1\ \mathrm{J}$$

Question 6

A $$1\ \mathrm{kg}$$ block slides down a frictionless incline of height $$2\ \mathrm{m}. $$What is its speed at the bottom?

Accepted Answer

$$4.43\ \mathrm{m/s}$$

Question 7

A $$0.5\ \mathrm{kg}$$ ball is thrown vertically upward with $$10\ \mathrm{m/s}. $$Ignoring air resistance, what is its maximum height?

Accepted Answer

$$5.1\ \mathrm{m}$$

Question 8

A hydraulic lift has a small piston of area $$0.01\ \mathrm{m}^2$$ and a large piston of area $$0.1\ \mathrm{m}^2. If a $$force of $$100\ \mathrm{N} is $$applied to the small piston, what is the maximum weight that can be lifted by the large piston?

Accepted Answer

$$1000\ \mathrm{N}$$

Question 9

A $$2\ \mathrm{kg}$$ object moving at $$3\ \mathrm{m/s}$$ collides inelastically with a $$1\ \mathrm{kg}$$ object at rest. What is the final velocity of the combined mass?

Accepted Answer

$$2\ \mathrm{m/s}$$

Question 10

A $$10\ \mathrm{kg}$$ object is suspended from a wire. If the wire stretches $$0.005\ \mathrm{m}$$ under the load and has a length $$2\ \mathrm{m}$$ and cross-sectional area $$0.0005\ \mathrm{m}^2$$, what is the Young's modulus of the wire?

Accepted Answer

$$7.84 	imes 10^7$\ \mathrm{N/m^2$}$$

Question 11

A $$0.3\ \mathrm{kg}$$ ball is dropped from $$2\ \mathrm{m}. If it $$rebounds to $$1.5\ \mathrm{m}$$, what percentage of its initial energy is lost?

Accepted Answer

$$25\%$$

Question 12

A $$0.5\ \mathrm{kg}$$ object is attached to a string and swung in a circle of radius $$0.4\ \mathrm{m} at$$ $$3\ \mathrm{m/s}. $$What is its angular momentum?

Accepted Answer

$$0.6\ \mathrm{kg\cdot m^2$/s}$$

Question 13

A $$2\ \mathrm{kg}$$ block is pushed against a spring (with $$k = 100\ \mathrm{N/m}) $$compressing it $$0.2\ \mathrm{m}. $$The block is released. What is its speed as it leaves the spring?

Accepted Answer

$$2\ \mathrm{m/s}$$

Question 14

A $$1\ \mathrm{kg}$$ object is moving at $$4\ \mathrm{m/s}$$ and collides with a $$2\ \mathrm{kg}$$ object moving at $$2\ \mathrm{m/s} in $$the same direction. If the collision is perfectly inelastic, what is the final velocity?

Accepted Answer

$$2.67\ \mathrm{m/s}$$

Question 15

A $$0.5\ \mathrm{kg}$$ object is dropped into a $$2\ \mathrm{kg}$$ container of water at $$20^\circ\mathrm{C}. If $$the object is at $$80^\circ\mathrm{C}$$ and the specific heat of water is $$4186\ \mathrm{J/kg\cdot K}$$, what is the final equilibrium temperature (neglecting heat loss)?

Accepted Answer

$$40^\circ\mathrm{C}$$

Question 16

A $$1\ \mathrm{m}$$ long rod is pivoted at one end and held horizontally. What is the torque due to gravity if the rod has mass $$3\ \mathrm{kg}$$?

Accepted Answer

$$14.7\ \mathrm{N\cdot m}$$

Question 17

A $$0.2\ \mathrm{kg}$$ object is moving at $$6\ \mathrm{m/s}$$ and strikes a wall, rebounding at $$-4\ \mathrm{m/s}. $$What is the change in momentum?

Accepted Answer

$$2.0\ \mathrm{kg\cdot m/s}$$

Question 18

A $$0.5\ \mathrm{kg}$$ object is submerged in water. If the density of water is $$1000\ \mathrm{kg/m^3$}$$ and the object has a volume of $$0.0005\ \mathrm{m^3$}$$, what is the buoyant force?

Accepted Answer

$$4.9\ \mathrm{N}$$

Question 19

A $$2\ \mathrm{kg}$$ object is moving at $$5\ \mathrm{m/s}$$ and comes to rest in $$0.5\ \mathrm{s}$$ due to a constant force. What is the magnitude of the force?

Accepted Answer

$$20\ \mathrm{N}$$

Physics Study Notes: Rotational Motion, Equilibrium & Elasticity, Momentum, Energy & Work, Using Energy, and Fluids

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