Work Done: Spring

Q.

In one of the exercises to strengthen the wrist and fingers, a person squeezes and releases a soft rubber ball. Is the work done on the ball positive, negative or zero (i) during compression (ii) During expansion?

1. While compressing; W_F = positive; while expanding, W_F = positive

2. While compressing; W_F = Negative; while expanding, W_F = Negative

3. While compressing; W_F = positive; while expanding, W_F = Negative

4. While compressing; W_F = Negative; while expanding, W_F = positive

Q.

A moving railway compartment has a spring of constant k fixed to its front wall. A boy stretches this spring by distance x and in the mean time the compartment moves by a distance s. The work done by boy w.r.t. earth is

1. $\frac{1}{2}k{x}^2$

2. $\frac{1}{2}\left(kx\right)(s+x)$

3. $\frac{1}{2}kxs$

4. $\frac{1}{2}kx(s+x+s)$

Q.

A body of mass 10 kg is dropped to the ground from a height of 10 metres. The work done by the gravitational force is $g=9.8m/se{c}^2$

1. - 490 Joules

2. + 490 Joules

3. - 980 Joules

4. + 980 Joules

Q.

What happens when a constant force is applied on a body in a horizontal direction?

Q. A spring force constant $k$ is cut in two parts at its one third length. when both the parts are streatched by same amount. The work done is

1. equal in both
2. greater for the longer part
3. greater for the shorter part
4. data insufficient

Q.

A block of mass 250 g is kept on a vertical spring of spring constant 100 N/m fixed from below. The spring is now compressed to have a length 10 cm shorter than its natural length and the system is released from this position. How high does the block rise from this position? Take g = 10 m/$s^2$.

1. 300 cm

2. 30 cm

3. 200 cm

4. 20 cm

Q. Two springs A and B are identical except that A is stiffer than B i.e., $k_A>k_B$. If the two springs are stretched by the same force, then

1. More work is done on B, i.e., $W_B>W_A$
2. More work is done on A, i.e., $W_A>W_B$
3. Work done on A and B are equal
4. Work done depends on the way in which they are stretched

Q. A 15 gm ball is shot from a spring gun whose spring has a force constant of 600 N/m. The spring is compressed by 5 cm. The greatest possible horizontal range of the ball for this compression is $(g=10m/s^2)$

1. 6.0 m
2. 12.0 m
3. 10.0 m
4. 8.0 m

Q.

If a spring of spring constant $k$ extends by $x$ on loading due to an applied force $F$, then the energy stored by the spring is

1. $\frac{F^2}{2x}$

2. $\frac{F^2}{2k}$

3. $\frac{2x}{F^2}$

4. $\frac{2F^2}{k}$

Q. A block is suspended by an ideal spring of force constant k. If the block is pulled down by applying a constant Force 'F' and if maximum displacement of block from its initial position of rest is $\delta$ then

1. $\frac{F}{K}<\delta <\frac{2F}{K}$
2. $\delta =\frac{2F}{K}$
3. Work done by force F is equal to $F\delta$
4. Increases in energy stored in spring is $\frac{1}{2}k{\delta }^2$