>PHYSICS

UNIVERSITY OF LAGOS

AKOKA, 2007

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1. A box slides down a smooth inclined plane 30m long and 10m high. Determine the speed of the box at the bottom of the plane if it start from rest at the top

A. 14m/s

B. 140m/s

C. 1.5m/s

D. 400m/s

2. A certain liquid has a specific heat capacity of 3.0kg 0 C. What mass of the liquid may be heated from 20 0 C to 50 0 C by 630J of heat ?

A. 4.2g

B. 7.0g

C. 10.5g

D. 11.4g

3. A steel rod, 2m long expands by 1mm when heated through 50 0 C. By how much will second steel rods, 1m long, expands when heated, through 25 0 C

A. 1/8 mm

B. 1/4 mm

C. 1/2 mm

D. 4 mm

4. A coil of resistance 3 ohm has an inductive reactance of 4 ohm. The power dissipated in the coil when connected to an AC supply of 50v rms is

A. 100w

B. 200w

C. 300w

D. 400w

5. A glass block weighs 25N, when wholly immersed in water, the block of glass appears to weigh 15N. The relative density of glass is therefore.

A. 0.40

B. 0.60

C. 1.67

D. 2.50

6. W hat upward force must be exerted on a 2kg mass to cause it to rise with an accleration of 1.5ms -2 ?

A. 22.8N

B. 2.28N

C. 3.20N

D. 2.0N

7. A stone projected horizontally with a velocity of 15m/s from the top of a building land at a horizontal distance of 60m from the buildiong. The height of the building is

A. 120m

B. 80m

C. 40m

D. 20m

8. C ompute the resultant and the equilibrant of the following system of coplanar concurrent forces: 100N, 240 0 , 100N, 30 0 , 141.4N, 45 0

A. 20N at 17 0 , 20N at 197 0

B. 151N at 205 0 , 151N at 197 0

C. 20N at 197 0 , 20N at 17 0

D. 151N at 25 0 , 151N at 205 0

9. A n ammeter of resistance R and reading up to 5A, is to be converted to one reading up to 10A. This can be done by connecting

A. a resistance R/e in series

B. a resistance R in parallel

C. a resistance 2R in parallel

D. a resistance R in series

10. A centre of mass 25kg moving with a velocity of 3m/s on a rough horizontal floor is brought to rest after sliding a distance of 2.5m on the floor. What is the coefficient of sliding friction between the crate and the floor ?

A. 0.09

B. 0.18

C. 0.36

D. 0.54

11. A vibrating wire of length L under tension T emits a note of fundamental frequency f. If a similar wire will emit a note of fundamental length 2f its length andd tension could be

A. 2L, T/2

B. 2L, T

C. 2L, 2f

D. L/2, T

12. R hythms broadcasting station transmit at a frequency of 93.7MH. What is the wavelength of the transmission

A. 3.2m

B. 32m

C. 32.2m

D. 32cm

13. T wo inelastic objects of masses 16kg and 4kg move in opposite directions towards each other with velocities of 3m/s and 5m/s respectively. Find the resultant velocity BV on collision if they are stuck together

A. 1.4 m/s

B. 14 m/s

C. 140 m/s

D. 0 m/s

14. A jack screw has a lever arm of 45cm and a pitch of 0.5cm. If its efficiency is 30%, what force F is required to lift a load w of mass 1200kg?

A. 6.0N

B. 69N

C. 0.69N

D. 690N

15. A body of mass 20kg, moving with uniform accleration, has an intial momentum of 200kgm/s after 10s, the momentum is 300kgm/s. Wat is the accleration of the body?

A. 0.5ms -2

B. 5ms -2

C. 25ms -2

D. 50ms -2

16. A n electron in orbit the nucleus made 300 revolutions per minute, what is the angular velocity of the electron ?

A. 300(22/7) rad/s

B. 30(22/7) rad/s

C. 10(22/7) rad/s

D. 3(22/7) rad/s

17. A battery of emf 24v has an internal resistance 12 ohm. The current draw is

A. 3/8A

B. 1/2A

C. 2A

D. 8A

18. In the radioactive series

235 –> 235 –> 234 –> 231

J K L M

92 93 91 92

The particles emitted are respectively

A. beta, alpha, beta

B. beta, beta, alpha

C. alpha, beta, alpha

D. alpha, alpha, beta

19. I f the pressure in a confined liquid is changed at any point, the change as transmitted equally to all points in the liquid. This principle is called

A. Archimede's principle

B. Flotation principle

C. Pascal's law

D. Boyle's law

20. A metal having a work function of 5.76eV is illuminated with a radiation of 7.88eV. The kinetic energy of the electrons emitted from the metal surface is

A. 13.64eV

B. 6.82eV

C. 4.24eV

D. 2.12eV

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