NEET Test Series from KOTA - 10 Papers In MS WORD
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PHXI03:MOTION IN A STRAIGHT LINE
362392
A man throws balls with the same speed vertically upwards one after the other at an interval of 2 \(s\). What should be the speed of the throw so that more than two balls are in the sky at any time? (Given \(g\) = 9.8 \(m^{-2}\))
1 Any speed less than \(19.6\,m{s^{ - 1}}\)
2 Only with speed \(19.6\,m{s^{ - 1}}\)
3 More than \(19.6\,m{s^{ - 1}}\)
4 At least \(9.8\,m{s^{ - 1}}\)
Explanation:
Let time taken by ball to reach maximum height be \(T\). Also \(v = u - gT\) At maximum height, \(v = 0\,\) So, \(u = gT\) \(u = 2 \times 9.8 = 19.6 \, ms^{-1}\) hence, the speed should be more than \(19.6 \, ms^{-1}\)
PHXI03:MOTION IN A STRAIGHT LINE
362393
A man throws a ball vertically upward and it rises through \(40\;m\) and returns to his hands, what was the ascent initial velocity of the ball and for how much time \((T)\) it remained in the air?
Velocity of descent or ascent always equal. \(u = \sqrt {2 \times g \times h} = \sqrt {2 \times 10 \times 40} \) \( = \sqrt {800} = 20\sqrt 2 \;m{\rm{/}}s\) Time of ascent and descent always equal. \(T=\) time of ascent + time of descent \(T=t_{1}+t_{2}\) Let \(t_{1}\) is the time of ascent and \(t_{2}\) be that of descent \(v=u-g t\) \(0=u-g t_{1} \quad v=u+g t_{2}\) \(u=g t_{1} \quad u=0+g t_{2}\) \(t_{1}=\dfrac{u}{g} \quad \dfrac{u}{g}=t_{2}\) \(T=t_{1}+t_{2} \quad T=\dfrac{u}{g}+\dfrac{2 u}{g}=\dfrac{2 \times \sqrt{800}}{10}\) \(T=4 \times \sqrt{2} \sec T=4 \times 1.41=5.64\) seconds
PHXI03:MOTION IN A STRAIGHT LINE
362394
A body falls from a height \(h = 200\,m\). The ratio of distance travelled in each \(2 \, s\), during \(t = 0\,{\rm{to}}\,t = 6\,s\) of the journey is
362395
A small body is dropped from a rising balloon. A person \(A\) stands on ground, while another person \(B\) is on the balloon. Choose the correct statement : Immediately, after the body is released.
1 \(A\) and \(B\), both feel that the body is coming (going) down.
2 \(A\) and \(B\), both feel that body is coming up.
3 \(A\) feels that the body is coming down, while \(B\) feels that the body is going up.
4 \(A\) feels that the body is going up, while \(B\) feels that the body is going down.
362392
A man throws balls with the same speed vertically upwards one after the other at an interval of 2 \(s\). What should be the speed of the throw so that more than two balls are in the sky at any time? (Given \(g\) = 9.8 \(m^{-2}\))
1 Any speed less than \(19.6\,m{s^{ - 1}}\)
2 Only with speed \(19.6\,m{s^{ - 1}}\)
3 More than \(19.6\,m{s^{ - 1}}\)
4 At least \(9.8\,m{s^{ - 1}}\)
Explanation:
Let time taken by ball to reach maximum height be \(T\). Also \(v = u - gT\) At maximum height, \(v = 0\,\) So, \(u = gT\) \(u = 2 \times 9.8 = 19.6 \, ms^{-1}\) hence, the speed should be more than \(19.6 \, ms^{-1}\)
PHXI03:MOTION IN A STRAIGHT LINE
362393
A man throws a ball vertically upward and it rises through \(40\;m\) and returns to his hands, what was the ascent initial velocity of the ball and for how much time \((T)\) it remained in the air?
Velocity of descent or ascent always equal. \(u = \sqrt {2 \times g \times h} = \sqrt {2 \times 10 \times 40} \) \( = \sqrt {800} = 20\sqrt 2 \;m{\rm{/}}s\) Time of ascent and descent always equal. \(T=\) time of ascent + time of descent \(T=t_{1}+t_{2}\) Let \(t_{1}\) is the time of ascent and \(t_{2}\) be that of descent \(v=u-g t\) \(0=u-g t_{1} \quad v=u+g t_{2}\) \(u=g t_{1} \quad u=0+g t_{2}\) \(t_{1}=\dfrac{u}{g} \quad \dfrac{u}{g}=t_{2}\) \(T=t_{1}+t_{2} \quad T=\dfrac{u}{g}+\dfrac{2 u}{g}=\dfrac{2 \times \sqrt{800}}{10}\) \(T=4 \times \sqrt{2} \sec T=4 \times 1.41=5.64\) seconds
PHXI03:MOTION IN A STRAIGHT LINE
362394
A body falls from a height \(h = 200\,m\). The ratio of distance travelled in each \(2 \, s\), during \(t = 0\,{\rm{to}}\,t = 6\,s\) of the journey is
362395
A small body is dropped from a rising balloon. A person \(A\) stands on ground, while another person \(B\) is on the balloon. Choose the correct statement : Immediately, after the body is released.
1 \(A\) and \(B\), both feel that the body is coming (going) down.
2 \(A\) and \(B\), both feel that body is coming up.
3 \(A\) feels that the body is coming down, while \(B\) feels that the body is going up.
4 \(A\) feels that the body is going up, while \(B\) feels that the body is going down.
362392
A man throws balls with the same speed vertically upwards one after the other at an interval of 2 \(s\). What should be the speed of the throw so that more than two balls are in the sky at any time? (Given \(g\) = 9.8 \(m^{-2}\))
1 Any speed less than \(19.6\,m{s^{ - 1}}\)
2 Only with speed \(19.6\,m{s^{ - 1}}\)
3 More than \(19.6\,m{s^{ - 1}}\)
4 At least \(9.8\,m{s^{ - 1}}\)
Explanation:
Let time taken by ball to reach maximum height be \(T\). Also \(v = u - gT\) At maximum height, \(v = 0\,\) So, \(u = gT\) \(u = 2 \times 9.8 = 19.6 \, ms^{-1}\) hence, the speed should be more than \(19.6 \, ms^{-1}\)
PHXI03:MOTION IN A STRAIGHT LINE
362393
A man throws a ball vertically upward and it rises through \(40\;m\) and returns to his hands, what was the ascent initial velocity of the ball and for how much time \((T)\) it remained in the air?
Velocity of descent or ascent always equal. \(u = \sqrt {2 \times g \times h} = \sqrt {2 \times 10 \times 40} \) \( = \sqrt {800} = 20\sqrt 2 \;m{\rm{/}}s\) Time of ascent and descent always equal. \(T=\) time of ascent + time of descent \(T=t_{1}+t_{2}\) Let \(t_{1}\) is the time of ascent and \(t_{2}\) be that of descent \(v=u-g t\) \(0=u-g t_{1} \quad v=u+g t_{2}\) \(u=g t_{1} \quad u=0+g t_{2}\) \(t_{1}=\dfrac{u}{g} \quad \dfrac{u}{g}=t_{2}\) \(T=t_{1}+t_{2} \quad T=\dfrac{u}{g}+\dfrac{2 u}{g}=\dfrac{2 \times \sqrt{800}}{10}\) \(T=4 \times \sqrt{2} \sec T=4 \times 1.41=5.64\) seconds
PHXI03:MOTION IN A STRAIGHT LINE
362394
A body falls from a height \(h = 200\,m\). The ratio of distance travelled in each \(2 \, s\), during \(t = 0\,{\rm{to}}\,t = 6\,s\) of the journey is
362395
A small body is dropped from a rising balloon. A person \(A\) stands on ground, while another person \(B\) is on the balloon. Choose the correct statement : Immediately, after the body is released.
1 \(A\) and \(B\), both feel that the body is coming (going) down.
2 \(A\) and \(B\), both feel that body is coming up.
3 \(A\) feels that the body is coming down, while \(B\) feels that the body is going up.
4 \(A\) feels that the body is going up, while \(B\) feels that the body is going down.
NEET Test Series from KOTA - 10 Papers In MS WORD
WhatsApp Here
PHXI03:MOTION IN A STRAIGHT LINE
362392
A man throws balls with the same speed vertically upwards one after the other at an interval of 2 \(s\). What should be the speed of the throw so that more than two balls are in the sky at any time? (Given \(g\) = 9.8 \(m^{-2}\))
1 Any speed less than \(19.6\,m{s^{ - 1}}\)
2 Only with speed \(19.6\,m{s^{ - 1}}\)
3 More than \(19.6\,m{s^{ - 1}}\)
4 At least \(9.8\,m{s^{ - 1}}\)
Explanation:
Let time taken by ball to reach maximum height be \(T\). Also \(v = u - gT\) At maximum height, \(v = 0\,\) So, \(u = gT\) \(u = 2 \times 9.8 = 19.6 \, ms^{-1}\) hence, the speed should be more than \(19.6 \, ms^{-1}\)
PHXI03:MOTION IN A STRAIGHT LINE
362393
A man throws a ball vertically upward and it rises through \(40\;m\) and returns to his hands, what was the ascent initial velocity of the ball and for how much time \((T)\) it remained in the air?
Velocity of descent or ascent always equal. \(u = \sqrt {2 \times g \times h} = \sqrt {2 \times 10 \times 40} \) \( = \sqrt {800} = 20\sqrt 2 \;m{\rm{/}}s\) Time of ascent and descent always equal. \(T=\) time of ascent + time of descent \(T=t_{1}+t_{2}\) Let \(t_{1}\) is the time of ascent and \(t_{2}\) be that of descent \(v=u-g t\) \(0=u-g t_{1} \quad v=u+g t_{2}\) \(u=g t_{1} \quad u=0+g t_{2}\) \(t_{1}=\dfrac{u}{g} \quad \dfrac{u}{g}=t_{2}\) \(T=t_{1}+t_{2} \quad T=\dfrac{u}{g}+\dfrac{2 u}{g}=\dfrac{2 \times \sqrt{800}}{10}\) \(T=4 \times \sqrt{2} \sec T=4 \times 1.41=5.64\) seconds
PHXI03:MOTION IN A STRAIGHT LINE
362394
A body falls from a height \(h = 200\,m\). The ratio of distance travelled in each \(2 \, s\), during \(t = 0\,{\rm{to}}\,t = 6\,s\) of the journey is
362395
A small body is dropped from a rising balloon. A person \(A\) stands on ground, while another person \(B\) is on the balloon. Choose the correct statement : Immediately, after the body is released.
1 \(A\) and \(B\), both feel that the body is coming (going) down.
2 \(A\) and \(B\), both feel that body is coming up.
3 \(A\) feels that the body is coming down, while \(B\) feels that the body is going up.
4 \(A\) feels that the body is going up, while \(B\) feels that the body is going down.