Pentru a scoate apă dintr‑o fântână, Ionel folosește dispozitivul reprezentat în figura 3, în care d = 20 cm și ℓ = 40 cm. Găleata plină cu apă are masa m = 14 kg. Calculează forța pe care trebuie să o exercite Ionel pentru a scoate găleata, acționând perpendicular pe manivelă, într‑o mișcare uniformă.VA ROG DAU COROANA

How does a circuit breaker protect a refrigerator? a. when the current is too high, a metal strip in the fuse melts and opens the circuit. b. when the resistance is too high , a re-settable which opens a circuit c. when the current is too high , a re-settable switch opens the circuit d. when the resistance is too high a metal strip in the fuse melts and opens the circuit

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is as it changes into other forms of energy.

Astone is dropped from the upper observation deck of a tower, 250 m above the ground. (assume g = 9.8 m/s2.) (a) find the distance (in meters) of the stone above ground level at time t. h(t) = (b) how long does it take the stone to reach the ground? (round your answer to two decimal places.) s (c) with what velocity does it strike the ground? (round your answer to one decimal place.) m/s (d) if the stone is thrown downward with a speed of 2 m/s, how long does it take to reach the ground? (round your answer to two decimal places.) s