A block of mass m initially at rest is dropped from a height h on to a spring of force constant k. The maximum compression in the spring is x then-

(1) $mgh=\frac{1}{2}k{x}^2$

(2) $mg(h+x)=\frac{1}{2}k{x}^2$

(3) $mgh=\frac{1}{2}k{(x+h)}^2$

(4) $mg(h+x)=\frac{1}{2}k{(x+h)}^2$

A spherical ball of mass \(20\) kg is stationary at the top of a hill of height\(100\) m. It slides down a smooth surface to the ground, then climbs up another hill of height \(30\) m and finally slides down to a horizontal base at a height of \(20\) m above the ground. The velocity attained by the ball is: 
1. \(10 \) m/s
2. \(10 \sqrt{30} \) m/s
3. \(40 \) m/s
4. \(20 \) m/s

The block of mass M moving on the frictionless horizontal surface collides with the spring of spring constant K and compresses it by length L. The maximum momentum of the block after collision is 

(1) Zero

(2) $\frac{M{L}^2}{K}$

(3) $\sqrt{MK}L$

(4) $\frac{K{L}^2}{2M}$

A body of mass m accelerates uniformly from rest to v₁ in time t₁. As a function of time t, the instantaneous power delivered to the body is 

(1) $\frac{m{v}_{1}t}{t_1}$

(2) $\frac{m{v}_1^{2}t}{t_1}$

(3) $\frac{m{v}_1{t}^2}{t_1}$

(4) $\frac{m{v}_1^{2}t}{t_1^2}$

A weight lifter lifts 300 kg from the ground to a height of 2 meter in 3 second. The average power generated by him is 

(1) 5880 watt

(2) 4410 watt

(3) 2205 watt

(4) 1960 watt

The average power required to lift a 100 kg mass through a height of 50 metres in approximately 50 seconds would be 

(1) 50 J/s

(2) 5000 J/s

(3) 100 J/s

(4) 980 J/s

The power of a pump, which can pump 200kg of water to a height of 200m in 10sec is (g = 10 m/s²) 

(1) 40 kW

(2) 80 kW

(3) 400 kW

(4) 960 kW

A 60 kg man runs up a staircase in 12 seconds while a 50 kg man runs up the same staircase in 11, seconds, the ratio of the rate of doing their work is 

(1) 6 : 5

(2) 12 : 11

(3) 11 : 10

(4) 10 : 11

What average horsepower is developed by an 80 kg man while climbing in 10 s a flight of stairs that rises 6 m vertically 

(1) 0.63 HP

(2) 1.26 HP

(3) 1.8 HP

(4) 2.1 HP